Hi Jed,
Implementing a cart will strongly depend on who you choose to process online payments.
Many merchant account providers will require their own list of compatible cart software.
Most merchant account providers use Authorize.net to pass data between the payment server & the sites generating the sale (your site)
PayPal is very flexible & includes all the tools needed
so you dont actually need software hosted on your site, they will generate a code snippet of HTML you put on your page. The cart & resulting checkout process is then further handled on the paypal server. Resulting orders are then emailed to you.
An old issue with paypal was that all shoppers needed a paypal account, or would be prompted to get one upon checkout.
Paypal now allows anyone with a major credit card to checkout without having a paypal account. Of course those who do have one enjoy the option of paying with any existing paypal balance, or withdrawing from their linked bank account.
Good luck!
