If it is an auction, the invisible hand of the market sets the price. In that situation, unless there is someone with less than 5 transactions feverishly bidding up the price, the chances of overpaying are small. If it is a best offer auction, bid at least half off and see if the seller bites. The asking prices are often inflated. If it is for sale only, it's likely inflated, but Google the item and see if something like it is being sold on the web.
It sounds like you didn't want to soend more than a couple hundred dollars and in that price range, the chances of getting scre wed are low, as long as the watch works.
What is post 1900? Post a link to an item you are interested and I'll have a look.