I haven't done what you're talking about butI can offer a suggestion based on my experience: offer them choices of how to pay. Some people like PayPal, some wan

I haven't done what you're talking about butI can offer a suggestion based on my experience: offer them choices of how to pay. Some people like PayPal, some want to pay by credit card, and still others want Google Checkout. If I had to guess, you should accept credit cards directly - so budget 3-10 days for developing that. Add another 3 days for PayPal and 1-5 days for Google (depending on what level of integration you want) if you choose to give your customers a choice. I suggest this because, when we offered a 2nd choice of payment on our sites, we found that we did 20% of sales through that 2nd choice! Was that 20% of sales who would've not bought the other way? Unknown but 20% is a sizable figure.