I already know that using server hardware is better, but I've seen others have success with consumer grade parts. Basically I'm looking at test home lab for ESXi 5.1. This is what I came across.
- Gigabyte 990FX-GA-UD5H (support IOMMU, VT-d)
- AMD FX-8350 8-Core CPU
- Intel PRO/1000 Dual Port Server Adapter
- G.Skill 32GB (4x8GB) DDR3 1866
- ATI Vide Card (PCIe), it's a spare I have
My main concern is the video card on it and whether or not it will pass through. I will be running ESXi 5.0u1 or 5.1 on a USB stick and have a ReadyNAS for Shared Storage via NFS.
I did find some Intel builds as well, but I'd save some money going the AMD route.