I have an off branded 15" Delta clone planer as well. There are a number of companies with the same unit, wearing a different badge, though all the badges look almost the same, just different letters/words. All of the ones I am aware of had the 2HP motor, where the Detla DC 380 was 3HP. That was the condition which they were allowed to copy. Mine is sitting on the wheeled roller base from Delta, with the twin roller extension tables, fits like a glove, because it is.
BTW I have seen the 3HP Deltas, used to own one, and I can't tell an appreciable difference in what this lower HP unit can do.
The Owners manual can be copied here
If you have the single phase variant it was the Delta model 22-680
A word about that site I linked to. You can completely view every page in the manual, however DO NOT hit the Download link, because it isn't about the download you want, it's some spamola BS from hell. It is entirely safe to go page to page, and copy them with a printer. I have used the same site for a number of other manuals, and have suffered no harm doing so. Actual downloads for the same pages cost about 35 bux online, and may. or may not be what is shown here.
As far as the deal, 250 is a really good price, if it is whole, and runs well. If you end up having to put a lot of parts/work into, well it may not be. I have an almost pristine model, with extra knives, and a setting jig, and I wouldn't take less than 500 for it. Compared to a 500+ DeWalley 735, it will eat it's lunch, and a few snacks, burp, and continue eating till that DeWalley is gone.