Authorize.net seems to be the bigdaddy in the space, and in my experience they're a pain to set up, but service is fine once you've obtained an account and wrap

Authorize.net seems to be the bigdaddy in the space, and in my experience they're a pain to set up, but service is fine once you've obtained an account and wrapped your head around thier Extensive but hard to navigate documentation/API. They also offer options of writing your own form and CURLing them to submit the data, or using one of thier forms, and they offer pretty good payment tracking (including search by cc data, and quickbooks files). Not sure about thier price point, but the few credit-card processing businesses i've worked with have all chosen it prior to my involvement, so i assume it's a good 'safe' choice.