For deals $20,000 or less, the transaction is completed by PayPal split into an initial and final payment. The initial payment is sent after the code upload is complete (don't worry, this is safely held in Fliptopia's secure servers until final payment is complete) and the final payment is sent after the transfer verification step by the buyer.
All deals over $20,000 are completed by bankwire. The buyer sends the bankwire in full to be held in escrow until the completion and confirmation of the transaction. Sellers receive the bankwire once the entire transaction is completed and deemed successful by all parties (i.e. when the app is transferred and both the buyer and seller confirm everything is as it should be). This process generally takes about a week, but is often shortened by parties that move quickly.