I have had good experiences shopping at gov surplus. I check out the Kansas State surplus in Topeka from time to time and am amazed at the deals. Dell Optiplexes, stacks of em', mostly with an i5 Core but some with the i7 for about $85-$125 bucks. I got a pair of Dell monitors for $5 each. Some PCs are labeled "parts" but these are fully functioning machines with the hard drive and RAM removed for some reason, again i5 or i7, $5 bucks each!

So, whatever state you may be in (USA) they are going to have a surplus store. Its worth a look where ever you may be.