Given the crappy picture in the ad and the total lack of details, no idea. Kind of looks like late 80s to me. When you go look at it, if it has indexed shifters, then it is late 80s or better. Most 90s bikes should have 7 speeds or more in the rear, while many 80s bikes are six speed, late 80s were often 7 speed. But for $85, you are not going to find much. Looks like a really basic bike in mediocre condition, well worth $85 IF you are able to do the work on it. If not, you will end up spending more on it than it is worth at a shop. Decent road ready bikes from the 1990s that are market priced will cost you $200 to $250. Since this bike is $85 and no one has snapped it up yet, I would assume it has some serious shortcomings.

But for $85, it can get you started (again, only if you do the work). Call a shop in your area, tell them you have a police auction bike that needs to be thoroughly rehabbed, and ask them for an estimate. Could be $250 or more.