I've only done short plays, so I'm not using up all that much paper (latest one is 10 pages), but I'd suggest doing full force 1 inch margins--maybe even an inch and a quarter--double spaced, and one sided. I need all the room I can get to make notes about costumes, edit, etc. The unused side can also be recycled (ripped into quarters for scratch paper, or printed on again).

When my friend, Val, was done with the first draft of her (not yet published novel) and wanted multiple copies I gave her $20 bucks, which prompted other friends to pitch in money, so--if you're comfortable with asking for donations--that might help.