Code name SDBK, just because it's too long, is the most complicated javascript / php application I've written to date. When you think of going on a tour or even renting a kayak, the last thing you expect is complex pricing system down to the very hour. What you buy right now could be different be different in 3 hours. SDBK is split into 3 checkout systems: Instore, Client-Side, and Concierge. They must all interact and work against limits set in the admin. These limits can be how many kayaks are in the water during a specific tour, too the amount of people are allowed. Lets just say... I hate kayaks with a passion. See more at San Diego Bike And Kayak