USPS has postal vending machines both in the office and a couple major supermarkets that eat bills up to $20. Same hardware the self-checkout machines use. Spits out $1 coins as change. So its merely four $20s, or so.

I've seen the same hardware spitting our arduinos and the like at hackerspaces. If you're worried about mechanical damage we have food vending machines at work that operate via locking sliding doors.