So, lately I've been getting into road bikes and have been riding my mom's old centurion, which is a good half-foot too small for me. So I'm looking to get an used road bike from the 80's, but I was wondering what the appropriate price for something like an 85 Fuji or Univega 12 speed road bike would be. Thanks.

The price depends upon the condition and where you buy it. Such bikes are sometimes found at Goodwill or at yard sales for $25. But, if you buy from a good LBS or a reputable E-Bay dealer who certifiy that the bike is in "good" riding condition, the price might be more like $125 to $200.

And, often, you will need to budget for new tires, new saddle, new pedals, a tune-up...a really nice 1985 bike restored to "excellent" riding condition can end up costing $300 to $400 by the time you are done.

Given that NEW 2005 road bikes can be found (especially during "special sales") for under $600, it may not seem sensible to "invest" $400 in a 1985 bike. Yet, if you find one with some attractive features (Reynolds 531 frame and fork, top of the line Campy or Sun Tour components, classic touring geometry) maybe spending $400 can make sense.

It seems as if most "fans" of vintage bikes have a good story about a $25 "find"...Not me, but tomorrow is another day.

the low-down on old-school Japanese bike values: https://www.sheldonbrown.com/japan.html

and everything else: https://www.sheldonbrown.com/vrbn-a-f.html