You most have gotten it off ebay then as in the US it is against the law to charge a surcharge and all so against ebay polices. Here is a link to RCmarts surcharges.
http://www.rcmart.com/catalog/paymen...eaeec70b01926e
With RCmart I have gotten 3 different prices and never know till I see it on my credit card statement what the final charge is One of the many problems I have had with them!