that antenna should be a breeze to install, normally a few bolts and a
plug harness, sometimes theres a seal.  as for price, im not sure what
a dealer charges, willing to bet not cheap for oem, but if you use
ebay replacements can be picked up for 15-50 dollars, depending if you
want aftermarket or a direct oem replacement, install time is about 15
minutes, take out the rear side panel and its right there tucked in
the quarter panel.  hope this helped a bit and good luck.

What do you mean by "dead"?  Does the motor run at all?  Is it the antenna
mast that is dead or the entire motor unit?

I replaced my mast on a 3000GT and was able to find a replacement for under
half the dealer price.  Funniest part is that the dealer also ordered their
parts from the same place in Milwaukee, WI and the unit was an EXACT factory
replacement.

Unfortunately part of the old nylon geared track got stuck in the motor, so
I needed to remove the inner plastic trim panel to get the  motor anyway.  A
few screws later and it was open and once cleaned out and reinstalled, the
new mast went in without any problem.

Here is the web site for power antenna parts:

      http://www.antennamastsrus.com/

Check out the site, it's worth the time.

 Bob