Keep a good life-vest in the budget. There are some nice "kayak specific" PFDs out there that really make paddling more enjoyable.
Same goes for a decent to good paddle, though a "good' touring paddle is half your budget easy, and not something you really need unless you are actually putting on 15+ miles a day touring in a loaded boat.
That said, I've had a lot of fun with the Old Town Loon 12-foot kayak that I keep at the cabin for the Mother-in-Law. The cockpit is big enough to fish from in comfort, unlike some of the more cramped "sit in" style kayaks.
And, while they are heavy, the two-ply plastic Old Town kayaks are tough.