The Perfume Shop

i have some old avon perfume bottles that still have perfume in them, i got them at a rumage sale this week end and i was wondering if anyone know where i could get prices for them so i know how much they are worth, i know they are really really old, like over probably 20 years, so if anyone knows, could you tell me thankx
but the thing is, i dont really know much about them, just what kind of prefune it is and who its made by, and what the bottles look like