Value - fine. $10 - $20 should skip past customs, plus if they open them, they'll have no idea of the value, so it should be a winner.
As for marking them "toys", that may cause problems for Europeans. There is some very dull law in Europe that says that all toys must have been tested to destruction and be safe in the process. Once they've been tested they get what is called a "CE mark". I have no idea what it stands for, but toys without this are illegal, as is the importing of them. This all sounds like a bunch of crap, but I have friends who have had prop packages marked "Toys" be inspected at customs and confiscated as the "toys" didn't have the CE mark.
Very dull, but from Europeans point of view, it would be better to have it marked "2nd hand shoes" or "2nd hand fancy dress costume parts" or something.
Si