Hi Mikah,
the ukash voucher is as is. You buy one at a shop (or by bank transfer) and you pay the amount you get the voucher for. When you enter the amount and voucher number in
EU.com you will get PEDs without having to pay the CC percentage.
I have only tried this with euro's and pounds, without a visible fee. Maybe the exchange rate is slightly in their advantage, but I have no reference material. Since you are in the US I think you can do a USD -> PED transfer at a rate of 1:10. Do they have outlets for the vouchers in the US? If you have to buy using a bank transfer, there maybe some money involved there (for the banks).
Now how does Ukash earn their money then... I am not too sure, but I guess
MA is paying them a fee for offering this opportunity to pump money into
EU.