title: In App-Billing possible as deposit
body: <p>Does anybody know if I can use the in-App billing as a deposit?
  I´ll explain it, we want to offer a game where users use our own phones, but we want to make sure they come back.
  So can I let a user pay an amount through in-app billing that I (without cost) refund after he returned my phone?</p>
  
  <p>I see that google charges 30% in the market for a transaction, how about purchases through in app billing? Can I use PayPal (since google only allows Google Checkout) for purchases of services and activities not software related?</p>
  
  <p>Thanks!</p>