Hey sonne.f,
I stayed at a hotel in Rome for about $100 a night. This might be out of your budget.
Please post your message in the hostel forum located here-
Lodging : Questions and tips - TravelPUNK Backpacker College Student Budget Travel Message Boards!
Many Travelpunks have been to rome on a tight budget and can help you if they see your post.
Thanks,
Tony