Paypal has many different types of accounts and many different rules that apply to them. Some accounts can only accept payments from the country you live in, some can't accept payments by credit card, some have huge fees attached to them, some have small per transaction fees. No account that i know of lets the person selling the item charge extra for people paying by Paypal to cover the fees, in any accounts i have experience with it is strictly forbidden and can result in penalties and closure of your account. It is a very convenient way to pay for things but the fees can get bothersome.

If you really take the time to read all of the fine print for all of the different accounts your brain will self destruct from all of the do's, dont's, sometimes can'ts and other good stuff.