> My only thought is that you could manage the shipping of the items--have each trader send you the item, where in you inspect it, and once you've received both

> My only thought is that you could manage the shipping of the items--have each trader send you the item, where in you inspect it, and once you've received both, you send both along, otherwise, you return the original widget to the sender. I wouldn't take the risk of confirming the value of products. Take the example of sneakers, there are plenty of knockoff sneakers on the market. You can usually tell, but if you aren't in tune with that market then you might well sign off on a pair of fake sneakers and become responsible for allowing a fraudulent transaction to take place.