If you don't want a merchant account, then you can take paypal, probably the largest third party processor in the world. you get a clear fixed rate, maybe 2.9-3.2%, and no fine print for surcharges or hidden fees.

If you're doing more than $35,000 a year in credit card transactions, paypal is more expensive than getting a merchant account through a reputable company. Under $35K a year, the costs and benefits are not so much fee related but service and feature related. Paypal is easy to use and easy to integrate into most sites.

Some companies, such as Heartland Payment Systems, which I represent, have a simplified pricing system for small merchants. Your "rate" consists of the cost that V/MC charges all processors, which is called "interchange", plus a flat monthly fee.

For customers using their bank checkcard Visa or Mastercard, which can be 60%+ of customers, you will save substantial amounts of money over Paypal. Again, this is ideal for merchants doing face to face transactions less than $50K volume a year.