that's craziness. you can buy a crazy billet aluminum aftermarket one for that much.
if you don't do the one above, and want a little more power output. the ones from the newest trucks are a direct bolt on. 220amp.
here's some posts about it.. he went a bit overboard with the fitment, you can just bolt it on and it's fine. part numbers are in the posts.
Just bought another alternator- #13534128. Seller had pics from all angles. Was listed at $135.96 but had a 20% discount code bringing it to $108.77. Add $10.28 in tax and I'm in it for $119.05. This one has 21,712 miles. New enough for me. No clutch. I dug through so many listings and...
www.tahoeyukonforum.com
I don't personally have one on my truck since my truck doesn't use an alternator, but I did put on my c6 with some case mods and it's a solid upgrade over that stock one.