The reason is probably due to eBay's spring seller update. It states:
"Sellers without a subscription will receive 20 free listings* per month, which can be used to create auction-style or fixed price listings.
For listings in the Collectibles categories, sellers will receive an additional 20 free auction-style listings* per month."
So from the sounds of it, you filled your 20 free auction/fixed priced listings with the video games and the Fashion Star Filly listing was free since there are 20 auction style listings reserved for Collectibles. Since video games are not categorized as Collectibles on eBay,listing any additional ones will cost $0.30.
Hope this helps