Your choices for Jeep alternators are basically Mean Green, PowerMaster and the shady
eBay sellers. The first are too expensive and none of the
eBay sellers seemed especially reliable (Iraggi, Alterstart, HO Alts), yet most on CA seem to be buying them. You might look at the 150A alternator part for th 5.9L Grand Cherokee P/N# R6041394AA. This is the refurb model and would give you 2160w to play with. Price is $152.50, but includes a $50 core charge, which I don't think you would qualify for. However, the one I received from the dealer has a sticker marking it as 137A, so I question whether it really is a 150A rebuild, but Kolak of JU fame swore up and down that his contact says this was a mistake.
Wycoff is the cheapest online dealer I have found:
http://www.trademotion.com/partlocator/index.cfm?action=searchCatalogOEM&siteid=213794