You may want to consider 2checkout.com - they are not bad. They have some issues, but some strong points too especially for the smaller shops. Your are looking at approx. $50 setup, then 5.5% and $.25 per transaction. http://www.2checkout.com .

You can also consider going the modernbill route and then backing it up with a merchant account and an authorize.net account. Generally here you are looking at $25 for modernbill leased, then another $20 - $30 per month in gateway and statement fees, then about 3% + $.30 per transaction. We work with a company called e-onlinedata who we met through modernbill.

http://www.resellerstreet.com/merchantaccounts.asp gives you some details on that merchant plan.