Can you direct me in the purchasing of a 1996 or 1997 cutlass supreme (Sedan)?

I'd start checking your local newspaper classifieds and calling around to local car dealers, esp. GM dealers, as often owners are loyal to the brand and when they go to trade their vehicle in, they will go back to the same place.  Since Olds is out of business the logical place would be another GM brand, or perhaps the same dealership, if it was mult-branded (i.e. Pontiac/Olds) and is still around.  You can get some decent finds on older vehicles this way as older folks trade them in with low miles.

try kijiji.com