I got about the same deal on a couple from the eBay as well. A friend of mine works in a machine shop, so I had him calibrate them for me as soon as I received them.
The instructions on how to calibrate the machinist level can be found in the above thread (2nd page I believe) Worked fine for me. But of course if you have a buddy that's a machinist, that's even better.
Starretts are the easiest to find and you can always sell them for about what you paid for them so their a good item to purchase. They are considered the standard for table work.