All online businesses try to organize credit card processing in the most suitable way. However “suitable” and “cheap” are not always synonyms when they describe a payment processor or a payment gateway. If your company does not have starting capital sufficient for licensing some open source payment gateway or for development of its own payment handling solution, then you should look for a provider of merchant services for startups, that is offering the functionality you need (not necessarily the “cheapest” one). Asking questions like “what is the best payment gateway for startups?” is not the right strategy, because the number of payment solutions for startups, that incorporate all the necessary logic, is very small. Here is the approach we recommend. First, you should conduct a reality check, i.e. estimate your processing volume and the revenue that your processor is going to get. Second, you should clearly specify all the functions you expect your processor to support. Third, you should check, which of the processors can support the functions you need in exchange for the estimated revenue. As a result, it may turn out that your choice is limited to one or two entities, offering the services of payment processing for startups.
More detailed information on credit card processing for startups is available in the respective article on Paylosophy.