Ah children. I think my daughter finally found the last few that still had their tags.
I concur with theirs and yours being the easiest method.
As for collecting rares, one thing that is relatively rare is the made in Portugal sealife, and the older models that say "made in Germany'. And some of the striped 75th animals.
I suggest setting a limit for how much you're willing to pay per item, with a max adj if you really want it. The hubs and I have slightly different standards for that. I try to keep below us$6 and he goes below us$10.
Collect what you like.
If you're from Australia, check out minizoo.com.au
He usually carries current models, and perhaps a few recently retireds. If nothing else might be a good price comparison...
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Laura