Well nobody made them buy the damn things. There was no reason at all to bring up their tard child either. What does the child liking this character have anything to do with her mental health?
Did they attempt to negotiate the asking price for the items, I wonder? Sometimes sellers have a Best Offer option on their listings where people can toss out a price lower than what's being asked. But even if that wasn't the case, if they had asked nicely, they might have been able to play the "bawww my chyuld is awtarded" card to score a slightly lower price. Unless of course it was an auction and not a Buy It Now listing, in which case the seller had zero control over the cost because other buyers drove the price up with bids.
I have never heard of Abby Hatcher, but I assume if these toys are going for that asking price, it must be at least somewhat popular. If many toys weren't made for it, then it probably means they are in demand by collectors. That's not the seller's fault.
Here's a fucking thought, Moo: commission someone to make a doll of the character. I guarantee it would not have cost nearly as much for something sewn or crocheted, unless it was absolutely massive.
Paying a small amount for an item originally and selling it for much more is called BUSINESS. Johnny Cupcakes shirts are a good example because with the exception of the original design, all his shirts are limited edition, and they often sell for a lot more than their original price on eBay.
The seller might be able to talk to eBay and get the feedback removed because it's unfair. Moo looked at the price of the items, agreed to purchase them, paid for them and presumably received them in the expected condition. No one forced her to buy them and the seller doesn't deserve to have their feedback tarnished because Moo can't say no to her tard.