I have one in used condition. It does the job well. 50.00 is a great price, especially since it is the asking price. I would offer 40.00 and go from there.
I think that is a great deal for that model. as far as that particular unit goes, ask to turn it on. Does it run quietly? run it with a bit in the chuck- does the bit wobble around (looks kinda blurry if it does). While the machine isn't running: Does the chuck (teeth, key) appear worn? Grab ahold of the chuck and give it a throttle. does it wiggle?
If you answer yes to any of those questions the DP is likely used to a point that much of the precision has been beat out of it. However that is a probably a good price, even if you part it out (in the classified ads here). The castings like the head, work table, and pulleys should pretty well help you re-coup your cost.
Just my 2 cents- ask around! There's a wealth of knowledge on this site
