For this exact type of thing, check out Dwolla. Paypal-style transactions (unique id is your email, but that's where the similarities end). It's run by a REAL bank (Veridian Credit Union, that's been around since 1934), and they do bank to bank transactions for 25 cents.
Disclaimer: I'm not in any way affiliated with Dwolla and don't gain anything by this post! Actually, as a business owner who accepts Dwolla payments, it would be nice to see this thing grow and become a standard thing people have to make it easier for everyone to pay each other, including me!