The used market is wide open, albeit, OPOS X-generation Summa cutters and Graphtec ARMS-equipped FC and Q Series cutters are the only solutions I'd suggest. Contour-cutting is very unforgiving; even tiny inaccuracies can trash high-value output.
In new, current Q Series and Graphtec 7000 (130 and wider) or SummaCut-R D120 (48" but cuts to the edge of thhe media) is the way to go. In fact, I think Summa deserves the nod on the contour-cutting side (sublime accuracy and automation); Graphtec/Q is superior from a cutting standpoint (cut quality and throughput).
Note that older Summa OPOS and OPOS 2.0 systems use red light scanners, which are not as reliable at reading marks through lamination. If you find a killer deal on the prior OPOS technologies, a good workaround is to put small pieces premask over the OPOS reg-marks prior to laminating. Then cut away the lamination/premask to reveal the marks. It's a small added step if your volume of contour-cutting is modest. If you'll do a lot of contour-cutting, I'd stick with OPOS X / ARMS exclusively.
Whew! Sorry for the verbose post.
Best Regards,
Jim