I don't know about you, but when I see "add 3% for Paypal" I'm immediately turned off. Why? I hate math. And if I see an advertised price I like, I don't want to see add-ons after I open the thread. Walmart won't ask you for an additional 3% credit card fee - it's built-in to their prices.
On eBay (I don't like eBay, really) they will not allow sellers to demand Paypal fees, for good reason: It turns buyers off! Same here, as far as I'm concerned.
I urge sellers to emulate Walmart and eBay. If I see the 3% hike on an ad I will simply refues to buy, no matter how much I want the item.
Sorry for the off-topic post.