It seems the OP is not as concerned with the up-front payment as with the method of payment being one with no recourse in the event something ends up janky. Credit cards and regular PayPal offer some level of protection for the buyer while money orders, cashier's checks, wire transfers, and PayPal F&F do not offer protections. I suspect more sellers are asking for payment by F&F, wire transfers, and money orders because they don't want the amount of sale recorded and reported to the IRS. Assuming sellers bought the stuff in the first place, the IRS reporting is easy and virtually nobody here should have a taxable gain of any significant amount. However, some people just don't want to be bothered.
If you want protection for expensive purchases as a buyer, simply offer payment by PayPal, offer to pay the associated fee, and walk away if the seller doesn't agree. It may cost you a bit more, and you may lose a few deals, but you should have greater piece of mind that you won't get swindled.

