Server Rack

As I recall the HP and Sunfire both have a 1U form factor. I would just shop the net on price, as other than the rack kits which you will need to get from the manufacturer's, you should be able to use most anything.

I've ordered a lot of stuff from http://techrac.com for small clients. Depending on your needs, one of the desktop cabinets might more than suffice.
http://www.techrack.com/catalog/product360.html

I recommend the Great Lakes ES480 it's short but has plenty of room for cable management, equipment and power.

http://werackyourworld.com/products/enclosures/es-series/gl480es-2442/