Most collector websites report that Beanie Babies - especially rare beanies like the Princess Diana bear - can be worth hundreds of dollars. However, a quick search of an aution site like eBay (http://www.ebay.com) reveals many Beanies are listed started at pennies, but there are hardly any bidders. Remember, a collectibles like this are only worth what someone will pay for them.
There are some Beanie Babies that are still worth some money but they are the extremely rare ones and have to be in mint condition. For more information about Beanie Babies please visit http://www.ask.com/wiki/Beanie_Baby.