I did this same exercise circa 2002. At the time there really weren't any good options (at least none that I was aware of) so I was pretty much charting my own

I did this same exercise circa 2002. At the time there really weren't any good options (at least none that I was aware of) so I was pretty much charting my own territory. It took the business well past $1,000,000 in revenue before they switched to some off the shelf package long after I had moved on. I guess it wasn't too bad for a comp-sci student with no e-commerce experience and little serious programming experience.