Most valuable toy: Bluebird Series Polly Pockets ($350)
Original price: $10-20
Selling for now: $10-$300
To have any significant worth, your Polly Pockets will probably have to meet a pretty precise package of parameters (sorry, couldn't resist the alliteration). As with many other popular vintage toys, eBay has drafted some guidelines for determining the worth of vintage Polly Pockets. Polly Pockets that go for hundreds of dollars were manufactured before 1998 when Mattel took over production from Bluebird. Bluebird manufactured 350 sets over the decade that they were in the Polly Pocket business, and only a handful command more than a hundred bucks. So, your vintage Polly's could fetch you something like this:
If your Polly Pocket appraisal game needs help, consult OnlyPollyPocket, the leading site for all things Polly.