ditto plush lore? im super ignorant and want to know

i bought my girlfriend and i two of the ditto line plushies that just came out (sabelye and squirtle) and i saw on ebay that some of them are significantly more than twenty dollars. i was wondering from the community if there was any lore on this specific line or if the plushies are really collectables like that.

to highlight: my intention is not to (unusable word that rimes with "alp") from other ppl like me who just like pokemon, i am just interested in some community lore that i am not familiar with.

if you know please let me know cus we are both wondering. thanks fans