I don't want to have to become a reseller because that would entail doing my own billing and customer service (and by looking through here it seems like more than a few people are having trouble doing that with all their clients). I'd still like to be able to offer domain registrations to a registrar on a smaller scale though. I would like to implement my system to use one time codes.

When the client wants to redeem their domain they enter a code like, "GFS85HJ" for example. This could be done on the registrar or my own site. It doesn't really matter to me. Ideally I would rather have it on the registrar's site so I don't have to integrate an API.

I've looked at RegFly.com but I'm a little wary with what went down before. They don't have exactly what I'm looking for but their API can use the PHP POST and GET syntax which with a little studying I might be able to implement on my own. I'd still rather be able to buy like 25 domains that come with 25 individual codes that can be redeemed one at a time.

Any suggestions are appreciated, thanks!