Dell Inspiron 3647
Just getting started with pfSense and was able to get a pretty good deal a couple weeks back on the Dell Inspiron 3647. This was the cheapest small form factor desktop they offered that had two available PCIe slots for NICs.
i3-4150 Processor (3M Cache, 3.5 GHz)
4GB Single Channel DDR3 1600MHz (4GBx1)
1TB 7200 rpm Hard Drive
I then installed two Intel EXPI9301CTBLK 10/100/1000Mbps PCI-Express Network Adapters.
I've been running a couple of weeks now and everything seems to be running smoothly. May consider adding another 4GB of memory in the near future. Anyway just thought I would share in case anyone was considering Dell as an option.
Dell Inspiron 3647 -http://www.dell.com/us/p/inspiron-3647-small-desktop/pd?oc=fdcwst313hw7