Don't mean to be cruel, because it's hard to comment on a car one
hasn't seen, but...
Some things on older Corvettes are rare because they were little-known
options that only people plugged-in at Chevy knew about (like special
powerplants or suspensions known only to professionals in the racing
industry), some were rare because normal buyers straining to afford a new
Corvette just couldn't justify the additional cost (like fuel injection
& air conditioning)
or felt the option would detract from street driving (like 4:55
differentials & side pipes),
and some years are especially appealing (57, 63, 67).
...but some things are rare because they just weren't appealing, (like
radio delete);
I suspect your color is in the last category, and probably still is.
Your Corvette sounds
as though it's barely more than a parts car at this point, it even has
to be hauled away
due to the steering problem, and it would cost a buyer upwards of $20K
to restore it,
so your best bet may be to offer it up to the highest bidder on eBay.
Watch eBay sales
for awhile to see what similar cars are bringing, and set your
expectations accordingly.

===================================

Rare Colors were generally the least popular (that is UGLY)
But a quick check shows that the Steel Blue was the rarest 75 Color
Try selling it as the last of the C3 Convertibles instead of its
color..IF you are pushing "rare"...

From your description of the car it is really a parts car or a long
term project car to be rebuilt...NOT RESTORED  
Rebuilding costs  could easily top  15K Restoration costs would
be 2 to 3 times that...

Put another way...
I own a 72 Convertible
A 76 Coupe
And a 79 Coupe.
.
None of them need anything   mechanically or cosmetically but I still
could drop a grand into each IF I wanted too.

I could walk out to the garage now, dust any of them off, spent 30
minutes with a detailing spray, drive them to enter them in a Corvette
Show and do well....if not win my class ...

IF I Put a 4 Sale sign on all three ..and sold  all 3
I would be lucky  (and surprised) if I could deposit
40 Grand in the bank this evening.....

My guess on its worth as it is now to someone like me who just enjoys
rebuilding cars for relaxation as a hobby...and as a  to keep me out
of bars is  $2,000 tops...

Bob G.
64 72 & 98 Rag Tops
76 & 79 Coupes

As others have said, you are in the roughest spot to be with a Corvette.
The year is against you, the condition is against you, and the market is
against you.

You already know, I'm sure, the costs needed:
1. Bumpers - $500
2. Interior - $800-$1500
3. Paint - $3000 - $8000
4. Engine rebuild - $4000

You can see this could be $15,000 in costs and it would be only halfway to
being a really nice car, since you still need to rebuild the chassis to be
up to the rest of the car.  While the chassis parts won't cost that much,
the labor will kill you.

Here's a link to what yours has the potential:
http://cgi.ebay.com/ebaymotors/75-Convertible-4-spd-hard-top-low-miles-NOM_W0QQi
temZ4619198957QQcategoryZ6168QQrdZ1QQcmdZViewItem

Here is a link to those selling on ebay now:
http://motors.search.ebay.com/Corvette-1975-75_Passenger-Vehicles_W0QQcatrefZC12
QQcombineZyQQfclZ3QQfromZR10QQfsooZ1QQfsopZ1QQftrtZ1QQftrvZ1QQmppfqyZCorvetteQ20
Q281979Q2c79Q29QQsacatZ6001QQsamcmZ6001QQsaprchiZQQsaprcloZQQsaspiZ2QQsatitleZCo
rvetteQ20Q281975Q2c75Q29

Here's a link to those that sold on ebay:
http://motors.search-completed.ebay.com/search/search.dll?sofocus=so&sbrftog=1&s
aspi=2&samcm=6001&from=R10&catref=C12&mppfqy=Corvette+%281975%2C75%29&fcl=3&comb
ine=y&satitle=Corvette+%281975%2C75%29&sacat=6001%26catref%3DC6&fsop=1%26fsoo%3D
1&a39=-24&a38v1y=&a38v2y=&a10239=-24&gcs=13&pfid=2473&reqtype=1&pfmode=1&alist=a
39%2Ca41%2Ca38v1y%2Ca38v2y%2Ca10239%2Ca3801%2Ca85%2Ca10246%2Ca33512%2Ca10241&pf_
query=Corvette+%281975%2C75%29&sargn=-1%26saslc%3D2&sadis=200&fpos=34471&fis=2&f
trt=1&ftrv=1&saprclo=&saprchi=&so=Show+Items

Realistically, to get the prices of some of these cars, you would need to
restore it.  So figure $20,000 on the low and $30,000 very likely.  Now what
could you sell it for restored?  Obviously, this makes the initial
investment very, very low, which isn't what you want to hear.

The best bet is put it on eBay and see what you get, or take it to a
Corvette show/swap meet or larger Chevy meet, like any of the Super Chevy
weekends.

Realistically, you can buy decent rubber bumper cars in the $6000 - $10,000
range, so even on the cheap (cheap paint and interior and bumpers), you are
putting it in the $4000 range as a high price and likely to be less.

Rare color is not going to do much for you, unlike midyears.  Rare colors in
them simply reduces the potential market to a much lower number of buyers.
Light colors seem to sell worse.  There is nothing like a good looking black
or dark blue to get people to notice, along with a deep red.

A guy I know of is trying to sell his '79 light blue. He is having a
terrible time and it is a really nice car.  He had it on ebay a few months
ago and it only went to around $4000.

Good luck.

Market:  For this car, geography is everything.  Can't really tell
whether you are in Florida, South Dakota or near Hearne TX.  Just for
chuckles and grins, let's assume Hearne.  That makes your 'parts car'
market Austin or Houston.  Your  'project car' market is closer.
Perhaps someone in Waco, maybe Austin. (An Austin techie who wants to
bend wrenches for a change.)  It's difficult to drive 100 miles each way
to see a car that you can't drive unless there are some real motivators.

Sounds like you don't need a tax write-off but if you did, a quick
donation to a Austin or Houston charity might be an option if you can
get a good FMV appraisal.  (Tougher now than three years ago but, if the
appraiser considered the core value of the two blocks, the individual
body panels, less wrecking costs, etc. etc.)  You might have $6-8K of
fair market value here and might be able to achieve a tax saving of more
than you can get for the whole car. (emphasize, "might")

Price:  Last month I put on my coveralls and helped a friend consider a
black '75 convertible.  Sharp paint, good frame, no rust, excellent/new
top, good trim and seals, fair-to-good interior--needed perhaps $ 500 on
the interior and another $ 500 in the front end.  The asking price was $
8,500.  There have been no takers and the car is now advertised at
$6,995.  I'd guess it will go for $ 6,500 tops.  Running C3s with
problems, particularly paint, advertise at $ 2K in the SoCal market. I
think you've seen honest estimates from this group and $ 1500 to 2000 in
the mid-Texas market might be about right.

Suggested Strategy:

1.  Define the car's build completely.  Engine, transmission, gearing,
options etc.  Have all this ready to send/fax/email to anyone who calls.

2.  Post pics on that website of yours.  Exterior and details.

3.  Advertise it as a project car within 75 miles of where you live
(Waco ?).  Then, advertise as a parts car in Austin and perhaps Houston.
 Try a couple of Saturday papers between now and mid-April.

4.  Contact Corvette clubs:  Sam Houston, Mid-Texas (Austin) and
Waco--google for the 'Con-Tex' in those clubs.  Ask for a "courtesy
announcement" for the car.  Provide a link to the photo website.

5.  Offer to charity.

6.  Offer to a salvage yard.

HTH & best of luck.  I'm outta here!