As mentioned its a little supply in demand and it comes down to what people consider them worth. Although, yes they are 1 in 24, they are not, in retail value, worth more than the RRP set by Funko (and stores, in theory, should not sell them higher than that) - the price you will have paid.
Anywhere that sells Funko figures there should be the opportunity to find a glitter; unfortunately with ebay scalpers and with people picking them up for trade fodder or to make some pony $$ means that they clear off of shelves fast. So well done on finding him and for retail price!
In general their resale prices do drop off; people scrabble and pay high sums and them eventually everything equalises out and most of them (minus the common RD and Muffin Pony) seem to sit about $50ish. Either way a great find! Well done.