After a quick search I could not quickly locate a comparison site for resellers. Your best bet would be to look at,

Authorize.Net Resellers

And pick one or two resellers from the official directory,

Authorize.Net - Reseller Directory

Or pick a local reseller from the official US state directory,

Authorize.Net - State Reseller Directory

And see if you can dig up any rip-off reports, complaints, or positive reviews that other people have experienced in the past. The truth is you are probably better off using your local bank instead of a reseller, because of the profit markup you would expect from resellers. Good luck on your search and please post your results. Curious to know what happens. Thanks.