So here's an interesting question, do you include the login/registration if there is only one product to purchase? I would assume that it seems a bit unnecessary to have a buyer sign up for an account if they are only buying one object and the purpose of the site is to sell this one object. IMO, the login is great for returning buyers, but in this situation we've got one product, one price, and that's it. What do you think?
In implementing carts for other customers in similar situations, the same point was brought up but in the end they decided they wanted to enable registrations for future usage ... like if they ever came up with another product or "add on" that made sense for their original purchase. More importantly though the FoxyCart version of an account really only takes an email and a successful checkout ... no multi-field laborious form prior to being "granted the privilege" of giving the shop owner your hard earned cash. Here's how we phrase it on one store in the checkout template:
"Eventually" has become my favorite word lately. It's good thing we do actually get some work done once and a while.