that seems really excessive for more coverage.... is that quote from your dealer? I purchased my 2002 Z06 Corvette which was just over 3 years old and at the beginning of a GMPP major guard warranty..... I extended it in the summer of 2007 for 4 years and the least amount of miles (I think it was 32K... dont have the paperwork in front of me right now).... I think it was a total of $1600 +/-
We also purchased a major guard GMPP for our H2 (which came out of factory warranty in September). I purchased 3 years and 24K of coverage (we dont put many miles on our rig) for around $1300-1400
I purchased both major guard plans from
www.gmoutlet.com these guys had the best price hands down on the GMPP plans, I spend a ton of time on the Corvette forum and this topic has been beat to death over there, I shopped the 2 best recommended (Fichter chevy was the other) places both times and this place had the best price.... my local dealer (where I know the service writer) quoted me nearly $2000 for the same plan. I would suggest shopping the above link before making your decision.
Good Luck