Nope! In general, most reasonable, full-price, shops will have some such any-reason thing, but it's not mandated by law. (DOA, of course, is required, unless you expressly sell it "as is", in which case you'd better price it accordingly.)

This makes it easier, I'm sure, for discount places to operate in the US, but it places the burden on the customer to figure out if they're dealing with a high-overhead, high-service shop, or some discount/deal website where you take more risk, and to choose which you do business with.

However, in the US (and in any civilised country), they can't throw new conditions on that were not revealed to you at the time of purchase. So the Paypal bit doesn't fly; a rip-off's a rip-off.