What I did:
Assemble random crap box from parts (Athlon 2100+, 512 MB RAM, 80GB HDD) This was free for me, and should be cheap or free for you. It was also two years ago, so you can probably find better hardware now.
Leave box at parents' house using cable modem for 2 months (free, but slow)
Co-locate box at Sprocket Data in Dallas for 6 months ($60/mo for 100 GB traffic, 100 mbps burst)
Then things changed a lot, but my startup has always owned all the equipment.
I like being able to fix problems myself when needed.