We have a webshop build with Xtcommerce (simular with OSc, only php is separated from html). XTc uses almost the same structure of OSc 2./2.3.
If you are interested in building an express checkout page for our shop, then please let me know and also inform me about the fix price for the job. I suppose that you develop this page with PHP + jQuery.
Bid on this project only if you have excellent proven skills.
You can get an impression of our shop at www.ts24.nl. Unfortunately it is all in Dutch.