Frankly, I think the service that PayPal offers is a bargain, at least for my purposes. I don't have to limit myself only to buyers that are willing to go buy a money order, I don't have to wait for the money order to arrive in the mail, and I don't have to cash/deposit the money order. My sales are typically under a couple hundred bucks or so, and the fees on that are only a few bucks.
I voted for "no", but I'm somewhat torn with the absoluteness of a Yes/No allowance or restriction to be required (and thus, somehow, enforced) by bladeforums. The Bladeforums Marketplace is not eBay. It's not the NYSE. It's not an internet "store". It's merely a bulletin board where people can connect with others to buy/sell/trade. And while BFC moderates and sometimes mediates and arbitrates deals-gone-wrong, BFC holds no responsibility or real authority over actual transactions. A scammer might get banned, but BFC can't force a reversal of funds (or, obviously, traded goods).
Bladeforums can certainly impose certain rules regarding PayPal (or similar payment methods). However, I wonder if Bladeforums has the right to say how we make our deals. Listings are public, but sales and agreements are often private, and frankly, really only concern the 2 parties involved. Expecting Bladeforums to enforce rules on how deals are negotiated would mean that it holds responsibility and accountability that it doesn't, and shouldn't have to bear. While it's true that the knife community is very tightly knit, and private sellers, craftsmen, and dealers have to pay a premium to sell here, when it comes down to it, the Bladeforums market is little more than a focused Craigslist or newspaper classified ads section. Obviously, Bladeforums doesn't want to be compared to the wretched hive of scum and villainy that is Craigslist, but neither can it be an all-powerful enforcer of barter, sales, purchases, and deals.