I would recommend teh Century Arms M70 Yugo underfolder build...well worth the money, around $400-500 depending on the source. The only downside seems to be that the barrels are not chrome lined, but they are underfolders which means they will hold value well, and the barrels are new U.S. made production, and seem to shoot quite accurately. I recently got one myself and feel it was well worth the money.
Vector Arms AK's seem to have a big following, and Vector has a 5 year warranty that they honestly stand by and a great fit an finish. The only downside is they seem to continuously jack their pirce about $25 ever three or four months as of late. Fixed stock rifles are around $500, about $575 for an underfolder. Atlantic Arms is offering a discount on these rifles if you are a board member, probably the best deal on them right now.
If he wants to go cheap, go to the local gunshop and look at Romanian WASR-10's, they are usually in the $350-400 range. On the downside they don't have "magwell dimples" so they aren't as "authentic" as the others already mentioned and may take afew minutes with a dremel to make a drum mag fit proeprly (easy to do), but on the upside they are cheaper. Fit and finish is worse, definitely want to handle the rifle you are going to buy, but on the upside they come with a sidemount scope rail, which allows relatively easy mounting if you spend a little on Commie optics (whcih are reasonbaly piriced) or a $40 siderail moutn with a weaver rail on top (which allows universal moutning of most scopes and red dots). Of course the finish can be fixed with a $3 can of brake cleaner for a degreaser, a $3 can of 1200 degree BBQ grill paint, and a couple of bucks of sanding paper, steel wool, and a wood finish of your choise. Seriously, the rifle will look much, much nicer of refinished by hand!