DPMS uses Magpul magazines.  I think Armalite has gone to these type magazines also.  Rock River once used FAL magazines.  I've seen the DPMS at Acadamy Sports, a local gun store, and Gander Mountain for around $1,200-1,300.  That leaves money for scopes or other accessories.  I've also heard some say they got 1/2 moa out of the box.  They seem to be a little front heavy with the colapsible stock.  Standard AR stocks seem to be more balanced.  I also think they are all eventually going to use the Magpul type magazines.  Several companies have adapted it.  I have an AR-15 DPMS and I like it.  No problems so far.  DPMS/Remington also make uppers for 243, 260 Rem, 7mm08, 308, and 338 Federal.  So you get a lot of options if you want to go that route.  Someone will eventually make it in a 358 also, from what I have read.  All of these cartridges use the same magazines, so that won't be a problem, like some calibers for the AR which require different magazines or magazine feeds.