As promised here are the specs on my new pfSense build.
Celeron G550 2.6Ghz (SB)
Cheapo Foxconn MB
Scavenged 4GB DDR3 1333Mhz RAM module (1x 4GB) - I can upgrade to 8GB later if I want more.
Dell X3959 (intel) dual port server NIC
Dynatron K2 CPU cooler for 1u case
Scavenged 2.5" 250gb HDD
16x PCIe riser card
iStarUSA 1u case with 220W 80+ PSU
A couple of 40mm fans.
Final cost was about $390 all in. A little on the expensive side but I'm getting a lot of use and fun out of it. I'm using a Netgear GS108E switch as well so I can play around with multiple VLAN configurations. Current services include snort, HVAP, pfBlocker, and nmap.