I had GREAT success using a website called Cardfellow.com . I'm not connected with them in any way....except as a happy user.
Cardfellow solicits bids from various merchant account providers. If you use one of their "bids" (for your business), the merchant provider....not you as the merchant.....pays Cardfellow a small percentage.
The provider they found for me has been outstanding. CF also provides an auditing function. Once or twice a year...I ask them to make sure I'm paying the best price. They also make sure that the Merchant services provider is charging you only what was quoted.