At that price you could get a few aluminum 80 cubic feet tanks. If you want to spend that much, I would instead suggest a 4500psi tank and a 4500 psi Shoebox. Fill the tanks to 3k if that's what your players are using, but you will get more fills before dipping into the 2k psi range.
If you (as in your group) are filling a 3k tank off of a 4.5k scuba you (as in YOU) need to be the one doing the filling so people don't overfill. I know 3k tanks are hydro'd at 4.5k, but they should only be filled to their rating at the field.