How do I know what I should sell my Princess Diana Beanie baby? Its a numbered edition with rookie card?

This is a first gen made in china 1997 Princess Diana TY Beanie baby, Mint contition. She also hace a rare beaded neclace that says princess on it. She has been kept in a plastic box. Ive checked the internet but cannot find anything besides lowball prices. I checked ebay and they ranged from 50-2500$. None of them have a rookie card or the neclace. She is made with PE pellets..Can anyone point me to a collector sight that isnt bogus or trying to rip me off?