Yeah, and RAM prices are ridiculous right now too. When I built the server, 16 GB ECC DIMMs were around $120 each and the 32 GB DIMMs were around $1000 (!!) each. The 32 GB DIMMs actually dropped pretty quickly and were in the $500-$600 range IIRC, but they're back up to between $700 and $800. The 16 GB DIMMs went up to around $220 IIRC but have dropped back down to a more reasonable $180. I've populated my board with 16 GB DIMMs so far and at 128 GB, I think I'm OK for now though I've been tempted to add another 32 GB. I'd like to add a "fast" array of SSDs at some point and put servers like SQL on it. Supermicro also released an upgraded BIOS and now certifies my board for up to 1 TB of RAM, so I should be set for awhile assuming ECC DDR3 DIMMs of the capacity necessary to hit 1 TB (64 GB, IIRC) are released at decent prices at some point.
Before this guy, my server was based on a Q6600 with 8 GB of RAM (max I could go) and six 750 GB drives in RAID 5. I built that guy in 2007 and the RAM became an issue for me, though amazingly I could get 6 or 7 VMs running if I was careful. Back then I used VMware Server but eventually I upgraded that old server to Windows 2008 R2 and now use Hyper V on it and run two VMs -- a second DC and a TMG server. I'm looking to replace it with a NUC at some point. I'm considering mothballing the old box when I get the NUC and at some point, maybe rebuilding it into a NAS as it has a nice case.