McDouglas seemed to have a talent for picking oddball engines for the later DC-9 series. The JT8D-209,17,19 is unique to the MD-80, so its costs are much, much higher today than the JT8D-7,9,15,17 that was on the DC-9. The BR-715 on the MD-95/717 was new territory, too.
Ironic then that the engine used on the "unsuccessful" MD-90 was the IAE V2500.
McD-D sold over 1,000 MD-80s and MD-87s, so there have got to be plenty of JT8D-200 engines in circulation, not as many as the original JT8D, but hardly uneconomic quantities for spares, etc.