Considering there's no Dust cover, And it may need a New Cartridge I'd say he's asking way too much. If it were a local pick up, I might offer $125. A Beautifull Technic's 1600 came up 10 minutes from my house in Showroom shape and Included a near perfect Dust cove for $150. I could kick myself for not jumping on it soon enough. That IMO was a Good deal.
At $300 shipped, you can almost buy a New Denon DP300F, that make no mistake, will run head to head with many Lower End Vintage TT's Including my Older Pioneer unit. Read the reviews for yourself. In fact that New Denon might be your best bet for around $300. It comes complete with Dust Cover, A New Decent Cartridge, a full Warranty and Its Properly set up. Used is fine if your handy with that kind of thing, I much preffer Turn Key...New.
Also check a local Stereo Shop you trust. Often people trade in late model TT's less than 5 years old that the dealer may sell for a good price and install and set it up for you if it needs a new Stylis or Cartridge. Still Pretty Much Turnkey.