There are MANY consideration in addition to the technolgy:<p>1. You'll get killed with currency conversions with PayPal. They're the equivalent of thieves in this regard. If you're expecting lots of non-GBP income, this could become a significant cost of running the business. But they're very convenient and easy to link to UK bank accounts.<p>2. Don't get married to one provider. Use a "meta" API like Spreedly (<a href="http://spreedly.com/" rel="nofollow">http://spreedly.com/</a> ) so that you can quickly/easily switch if something goes wrong. With all the "PayPayl is evil" stories of late, this is simply prudent. I haven't used Spreedly yet, but heard good things about them, and they answered a quick question I recently asked them.<p>3. Google Checkout is not as well-known as PayPal. Funny anecdote I can't find the reference for now: A website was using PayPal and thought to add Checkout, with both icons next to each other on the page. Their <i>Paypal</i> earnings shot up significantly, and Checkout got very little additional revenue.<p>4. If you accept credit cards for payment, ne careful with PCI compliance, even if you don't accept credit cards on your own servers: <a href="http://en.wikipedia.org/wiki/Payment_Card_Industry_Data_Security_Standard" rel="nofollow">http://en.wikipedia.org/wiki/Payment_Card_Industry_Data_Secu...</a> . If you process the CC info yourself, PCI compliance can be very expensive for a sole hacker or small business, so consider off-loading the processing to a provider. You'll still need to have some level of compliance as I understand it, but it's easier. IANAL so get proper advice from your lawyer and accountant type friends.<p>5. Taxes and HMRC. 'nuff said.