Actually gender has nothing to do with it.  I know way more guys who
have to much sunk into classic cars then women.  I'm quite sure the
Mustang shop did tell you that.  Especially if they can get you to
bring it in for more & more repairs.  

I sincerely think you should fix the interior and muffler if you
expect to get 7k.  Most definitely the muffler screams "I've never
ever cared about/for this car.  I would never ever put a car up for
sale that needed a muffler.

Do get all freaky deaky just because people are having a conversation.
This isn't the greatest forum to get top dollar for a sale anyway.

That the longer you have it the more it will be worth, true, provided
it's condition doesn't go down.

You were initially asking 10 grand for a car with pretty pictures of the
outside and then admited "rest" (rust,obviously) underneath and interior
(headliner none the less) and muffler issues. You have no pictures of
these trouble spots.

I've seen LOTS of pretty old fords that looked like sh.t when I crawled
under them. Each owner was asking top dollar for their pretty mustang.
(and none of them needed a headliner, which is, as I recall, a big job
that requires removing front and rear glass.

I've crawled under these pretty mustangs to find rust holes in a the
floor patched by taring a piece of sheet metal over them under the
carpet. Frame rail rot that meant tearing the whole car down to replace
the rail. Torque boxes that were all but gone. The list goes on with the
horrors I've found under 'pretty' unit body fords.

This has nothing to do with you being a woman, but what you have
presented to us and the price you are asking for it. I'd never buy a car
online that someone admits to rust on the underside, I've seen owners
represent their cars as top quality and have serious rust issues
underneath. What is nothing of concern to most people on the underside
of a car is of big concern to people who know what they are looking at.

Yup.  Little niggly things like that detract from the value of the car
more than it would cost to fix them.  Though a torn headliner is a
supreme pain in the rump to fix.  I had a very small tear in the
headliner of my old '67 and I just paid someone from a tailor shop to
come by and "micro-stitch" it without pulling it down, but I just got
lucky because it was a very small tear.  You could see the repair if you
looked close, but it looked a LOT better than having a Dorito-sized flap
hanging down.

Also, if there is "rest underneath" that is a big red flag on these
cars.  In climates with snow/salt or people near the ocean, rust can
quickly do a substantial amount of damage to the frame rails, torque
boxes, floors, trunk, bottoms of the fenders/doors, etc.  Replacing
floorpans and frame sections is very much NOT fun.  I've actually had
one '67 where I physically cut the frame off north of the firewall and
welded on a new frame section from a '68 cougar.

If the original poster would rather keep it than just accept the reality
of the going rate for these cars, then why bother advertising it in the
first place?  *shrug*

Cheers,