Hi Kim...it depends on condition, year, and your area, a picture would be of great help. In general terms, if it is modern and we'll used it could be as low as $300. If it is ~1980 and perfect it could be several thousand $$$.
I see modern ones around $500-700 average... exceptional condition or desirable colors will increase it.
Pics please, especially if you are local to me because I've been looking an OM Flyer for a while .