I've been looking at used Xterra 505's in that price range,
And sometimes a 705 comes along at a good price in the 4's .
Heck I just found an old whites 6000 DI pro SL for $50 not working.
Sent it to Whites for an overhaul - $100 (a thank you to the folks at Whites).
So for $150 She's an awesome coin hound!!
And it too does the everything you asked for above.
Find a used AT pro and now your fully submersible.
And I'm seeing Tersoro Sand Sharks in the 4's as well.
I read that they are good starter submersibles..
I may get one some day..
Loco-digger is right that at $300 retail, you cant get much.
But be patient and prudent and good used machines come along quite often.
Cheers