I'm sorry, what? I can 'buy' money from the Play Store? When I tap the three dots next to a paid app in the listing, I get two options. One is to add to wishlist and the other is to 'buy £2.99'. I am sure there must be an explanation for this error.
No, it means that the item costs 2.99 pounds. Wishlist is just a personal list where you can add apps that you're considering, kind of like a shopping list.