There are 2 ways of doing a "credit spree"
Example 1 (most commonly used method): Person A has Minnie Ears and wants a 10,000 "credit spree" for it. They will most likely be looking for the current 10,000$ magic in the shop (currently zombie). So you would buy them the magic and you would get the item. That is the most common form of a credit spree
Example 2 (not used as often): Person A has Minnie Ears and you want them so they ask for pure 10,000 credit spree meaning you buy 10,000 credits worth of pixel's. This is a tedious method but pixels sell for there credit amount. Meaning they sell for as much as was used to buy them. This way the person actually gets credits not just an item worth the credits. This form isn't used that much anymore but i still see it happen.
Hope this helped!