Is there a specific feature you need on the 2312 that isn't on the 2112? 2112, 2312, and 3312 all have MultEQ XT room correction and very similar amp sections, so they will all sound pretty much the same once they are set up. The big advantage of the 3312 is the preamp section in case you want to add external power.
Read the first three posts of this thread, determine the features you need or want, and buy the cheapest one that meets your needs.http://www.avsforum.com/avs-vb/showthread.php?t=1334369
Also, here is one of the "deals" thread that may help with shopping tips. The 2112 streets for <$450 right now, which is a pretty good deal.http://www.avsforum.com/avs-vb/showthread.php?t=1388096