Thats good. I will give it a try and report back tonight then. Hopefully I can tailor it to my needs.

Your screenshots bring up a question though: Is this site-wide or per user min/max? My goal is to prevent 1 user from adding the same product another user is in the process of purchasing.

It may just be wishful thinking but I figure if they do radio ads for example, there will be a burst of traffic and users may try to buy the same item. I want to eliminate the 'race' to checkout.

Essentially I will need to trial run this and a few other ideas in my head and see what I can get working. I can't promise my solution will be pretty by any means, but if it works, thats all I can ask for. We can bother with standards later...