I'm quite sure that 500 peso note is "old pesos" and therefore virtually worthless. Though not totally worthless, if 500 "new pesos" are worth $27, then 500 old ones are worth 2.7 cents. And it's in such bad shape I can't see it attracting much attention on E-Bay. See here
, they had a big remonetization in the early 90s.
Sorry to dash your hopes. I think all of the cash handed out was in the same boat. I thought about tossing in a few loonies, but I think they are still worth a little something... :-)