Pricy, at 85 Grand or so. But available.
You'll also need the co-ax and top machineguns, ammo, OVM, radios and most of all, a trained and experienced crew. Not a problem; all those things can be had too. You just have to know where to look, or get someone who does as your first acquisition.
Fortunately, you've already made contact with someone with experience in old Polish T-55Ls as well as most U.S. armor of the previous five decades.