All that for ten people? Wow.
I worked at a pharmacy benefits company with a comprehensive system that managed cardholders, drugs, plans, prior authorizations, etc. I wrote the data dictionary for the system which consisted of about 200-250 tables for various purposes. Some of the logic was kludgey, some of it was pretty ingenious. It was created in Oracle and scalability never seemed to be a problem. I would guess they managed about a million cardholders all told.
Of course, eBay's pretty much killed the business - we're just on liquidation mode now with the most recent ‘changes to better service the customers’ - IE: more fees raised and more demands to make shipping free, while shipping becomes ever more expensive.
Though the bright spot was a couple days ago - Economics graduate who does shipping part time finally figured out that the business is unsustainable between eBay fees and eBay (Paypal) fees. Then again, got a call from a competitor asking if we wanted to buy them out, offered to sell out to them.
Long and short of it, eBay's wanting to only cater to small sellers in the US, and giving away the store in Asia. Our eBay/paypal fees would be a quarter of what they are now if we were based in Hong Kong selling the same products.