I could well be wrong, but I don't think Virgin MegaStore is on Pleasure Island - I think it's in the West Side. We walked through the Pleasure Island bit during the day and it was just bars, I didn't spot any stores.
Yup - here you go, Virgin MegaStore is on the WestSide
Downtown Disney
Pleasure Island is in the middle, that is the only bit that you need tickets for, and MarketPlace is on the far side, if you want to get from West Side to MarketPlace there is a path that goes around PI so that you don't have to pay,
Bev