Small Toys For Kids

Where can I get a lot of small animals "toys" – vertebrates and invertebrates?
I'm doing a class of 23 children and I want to learn the group of vertebrates and invertebrates. Something like http://www.amazon.com/Learning-Resources-Fun-Fish-Counters/dp/B000296LPM/ref=pd_bxgy_t_img_b But I need to mammals, insects, jellyfish, reptiles, amphibians, arthopods, etc., and preferably less than $ 20-30?
I found these at Walmart and on .. Dollar Tree, but not all the time. Of course teacher stores have this thing a bit, as specialty toy stores, but can get expensive. I've seen "lots" on eBay. You can try this approach. This is much smaller ocean. Http: / / cgi.ebay.com/12-vinyl-OCEAN-ANIMAL-Favors-Seal-Turtle-Fish-Party-NIP_W0QQitemZ370145542506QQihZ024QQcategoryZ102421QQssPageNameZWDVWQQrdZ1QQcmdZViewItem Some more ideas .. http://search.ebay.com/search/search.dll?from=R40&_trksid=m37&satitle=plastic+animals+lot
Small Toys, Big Kids