R.G.
We don't have very much money so we always just give $15 to non family grads. It's just our rule. If we don't know them too well (i.e. a neighbor) we'll do $10. Since it's a rule, I don't feel to guilty about not giving more. You don't want to overgive, think after Christmas credit card bills. :) Just spend what you can. If ten people give them $15 that's $150 they didn't have. Besides, every little bit counts to a new grad! If it's a close family member we will do $50 but these come more spread out.