Are the computer parts refurbished? Otherwise I wonder where do you get 2GB RAM, 80GB HDD, and other older components at good prices these days?
Usually, parts get cheaper as the become replaced by newer versions, but then become expensive again.
Edit: If you're in the UK and happen to want a supply of EOL computers, I suggest Morgan Computers, e.g. http://www.morgancomputers.co.uk/product_detail/14905/HP-Eli...
Is it really? It seems in line with eBay/Craigslist prices for similar hardware, expect for the "remanufactured" part.
I agree with you on the testing; if it's rigorous enough that will likely the biggest sale point.
One quote from the company and a definite (back to base) guarantee would be more acceptable to accountant than lots of small transactions on ebay/local suppliers.
We're talking about a use case where spending $500 to ten-tuple a users peak computational ability is too much of a capital investment and/or labor is too cheap to bother, so just hire more bodies and work slower.