I've found a number of sellers just aren't aware that passing on a surcharge for paying by Paypal is wrong. Every time I hear from a seller trying get me pay a surcharge for paying thru Paypal, I simply submit my payment without the surcharge and include the same policy rsmiller40 posted above in the comments section with my payment. I explain that I will not be paying the surcharge since it's illegal and against the user agreement they have with Paypal.
I have actually had a few sellers thank me for pointing this out to them. Most of the time I don't hear anything about it. And I have never gotten any negative response from handling it this way.