keep look'n.
you can get a "j head" Bridgeport type mill for just a little more money. The tooling (collets) is unique to that model so expanding your tool set will be troublesome. You will most likely NEVER use the dual head feature, so that is just a waste of space.
About 5 mils slack in y-axis, 15 mils in x-axis feeds.
Most machinist would read that as "5 millionths of an inch". I doubt that, maybe he ment thousndths of an inch. Basicly the seller doesn't know much about what he is selling.
Ditto on the J Head BP.. Or, if you can get the seller to drop the price significantly.. and use that savings to hunt for tooling.. I have an older round overarm SB Lathe vertical mill.. got it cheap and cleaned and restored it, and love the hunt for tools to fit it.. All stocked up now ... and very useful when I need it.
A lot depends on what you're wanting to do with it.. if its hobby.. this solution could be fine. If your after some serious money making .. The J Head is the way to go...