The local parts store is the way to go.  Much of what Eckler's, Zip, and
others have is repackaged parts, so they add their markup plus they know
that adding "Corvette" to the sales sheet jumps the price.

The carb rebuild kits never have floats.  The floats are always separate.  I
doubt you can get them at Chevy anymore, but your Napa, Car Quest, or other
local parts store may have them.

Borg-Warner used to produce floats for many carbs.  You may have to find
someone that deals in Borg-Warner.

Borg Warner is a name brand with a good reputation, but... the 63
Corvette used a "multiple bent-finger centrifugal diaphragm" clutch,
which is different from the typical 3-pivot-lever designs. Perhaps
that's the difference in price? You can view the correct clutch in the
63 shop manual, or go to corvettecentral.com and search the C2 catalog
on "clutch kit" (you want the 10.5" version)and look at the picture
there; original was Chevy part #1841673 which is no longer a valid
number. Have you checked with a Chevy dealer to see if there's a
replacement part?

Been ages since I had a WCFB apart, but I'm thinking the floats were
brass, and if so, they can generally be easily repaired (soldered) if
need be. If you gotta find 'em, try a local carb rebuilder or even NAPA,
or someone known to rebuild Carter WCFB's (for example Dick Katter at
703-754-7547)

My local parts supplier offered me a Borg -Warner kit for approx. $40 less
and no shipping

BW makes quality parts and the one you get by mail order could just turn out
to be a BW.  Buy the clutch locally.

Where can I purchase floats for my Carter WCFB

Tougher to solve.  As I recall, the float was still formed brass.  Is it
collapsed or otherwise misshapen or does it just have a leak in it?  If it's
just a leak, and it's a brass float, find the hole, open it with a 1/16"
drill bit and drain it thoroughly.  Bake it at low temperature (150 F or so)
to drive out any residual liquid.  Solder the hole shut.  finding THE right
float may be a bit of a challenge.  It may mean buying a carburetor and
using it for parts.  Contact Contemporary Corvette in Pennsylvania at 800
367-8388.  Ask for Rocky.  If it can be had, they either have it or know
where to get it.

Charlie