The seller pays PayPal a % of the money they receive. These are the fees that keep PayPal in business, and you agree to pay when you set up your account.
PayPal offers a service for it's customers where two people with PayPal accounts can send each other money without incurring any fees. This is the "gift" payment. It expressly forbidden in the PayPal terms of service to send a gift to pay for goods and services. As a seller you could have your account suspended or even closed for abusing the gift payment.
As a buyer you have protections from PayPal against fraud. When you send someone a gift through PayPal you give up those protections.
If you are a shady seller the gift option can be used to beat PayPal out of their fees, and screw the buyer out of their purchase leaving them with no recourse.
If you are a buyer that pays someone for goods or services not yet received using gift, you are an idiot.
This thread goes back a long way and I'm disinclined to read it all the way through. I read the first few and last couple of pages. The thread's now about a month stale, but I'll add my 3% + 35 cents to the discussion anyway. I'll also quote FLymon as his post is directly to the point. I've bolded his last sentence not to add insult to those who've paid by F&F, but because it goes to the heart of the discussion. Why would you as a buyer break the rules and sacrifice your protection for a few cents on the dollar?
I do consider using the term "net to me" or some such phrase, asking for fees beyond the stated price, or making up some amount for fees (like 4 or 5%) to be petty and somewhat annoying. C'mon, just add the fee in as part of the price--how hard is that?
I don't let a "net ask" be a deal-breaker, though, if I want to make the purchase. If I'm meeting the asking price, I just add in the 3% and round up to the next dollar. I make this clear in my PM.
Generally, I'll make a somewhat lower offer (also by PM) for the knife anyway and make sure the seller knows that I intend to pay G&S. I might offer less than their net ask or offer to split the fees or to pay what they're asking but by G&S. I have never paid for a blade other than by G&S and I can't recall that insistence ever causing a deal to go south. Maybe we can't agree on a price, but if 3% breaks the deal, either you didn't really want to sell it or I didn't really want to buy it.
As with most things in life and in business, open and honest communication is the key.
BTW--I F&F'd a contribution the other day to someone helping out a sick friend. Paypal charged me the 3% plus .35. Is this something new?
Edit: I just checked out the Paypal site and I guess if I sent the money from a linked bank account or from a Paypal balance there would have been no fee. Because I used my debit card I guess it goes through as a credit card transaction and PP recovers the fee.