I go to the gym at my university.
£27 for the year.
If you were to do dumbells exercises and whatever, you're best to do them at least every other day. This gives you body to rest for one day at least. If your muscles still feel stiff (no jokes please) then do it once every 3 days.
I'm also trying to build my upper body at the moment. Sadly I'm doing it once a week. I've got other commitments.