Give it a few more years and it will be under $1K. It is 13 years old already and the game that replaced it (Afterburner Climax) is itself 7 years old. The places that operate the things should be starting to unload them in big numbers soon.
Unfortunately the 3-screen version is just too big a unit to get, even if the price is right.
It's funny that Afterburner Climax is not nearly as desirable to me. The gameplay is WAY too fast, and I don't think you can have a cockpit view like you can in Strike Fighter. The "realism" of Strike Fighter, combined with the arcade-like play really hit a sweet spot for me.
The best thing for me would be to find a bad 3-screen unit with working boards, then rip out the guts and build my own smaller cab with 3 LCDs. The outer 2 LCDs could even fold in or back when not in use.