On another forum (XDA developers) I was scammed when trying to purchase a cell phone from the marketplace. PayPal provided protection. In this case it was easy to deal with because the 'seller' never provided a tracking number and didn't respond to PayPal, so PayPal simply refunded my money. Just make sure you don't do gift option. I wonder too if you can request the seller to send you an invoice via PayPal with a list/description of the parts and pay per that invoice.