you are not allowed to charge a paypal surcharge but you can offer a discount for other payment options, I use this as it is within the rules of ebay and i am in dispute with paypal
I simply factor the on costs into my shipping and handling, obviously I make it fair and do not do any of the stupid rubbish like 99p sale price and £10.00 postage...
Factoring in your on costs is also within Ebays rules..