I have a 2U Dell Server that I picked up on ebay, that is more than capable of handling all my sites that I currently use a VPS for. I am hoping to keep my monthly charges well under $100, since I already have the hardware, and I'm paying under $50 for my VPS now. Dare I say, I would like my Colo charge to compete with my under $50 VPS charge, in an ideal world.
I've found some places for $40 to $60 per month that will host a single 2U box for you, but I was a bit unhappy with their bandwidth/speed specs.
I was curious if there were any recommendations for this type of provider.
A cheap VPS will almost always be cheaper, unless you're at a big scale. Partly due to access issues, and handling replacement drives/PSUs/etc, actually using a colo unless it is a gentleman's agreement will be more of an annoyance anyway.