Use this system to integrate payments with shipping and accounting.
In the old days, any seller who wanted to accept credit cards had to get a credit card merchant account. Now, payment services like PayPal [Hack #85] have made merchant accounts largely unnecessary for everyone but the largest sellers, but there are still reasons to get a merchant account. For instance, sellers who do a lot of business may be able to get a better discount rate as a credit card merchant than they could through PayPal, which essentially means they keep a larger percentage of the payments they receive. And anyone who sells merchandise outside of eBay will not want to limit their transactions only to PayPal.
If you use an off-eBay checkout system, you may wish to disable eBay's own checkout [Hack #64] to keep bidders on-track. Better yet, use a payment-collection system that integrates with eBay, such as Marketworks (www.marketworks.com).
But if there's any single truth when it comes to accepting payments on eBay, it's this: the more types of payment you accept, the more bids you'll get.