I have spent about $200 dollars so far in this game. It's the first game I have ever spent so much money in but I've been playing for almost a year now. Plus, I have made many friends from this forum and most have all the premiums. It got to the point where I decided I wanted those same things. (Wish I'd made that decision when Kang was available!) I don't plan to abandon the game anytime soon so it's an investment. As Jay_Kay said in an earlier post, you spend money on entertainment. That's what this is, at least for me.
I have bought the golden scratchers too. Won 6-9 donuts but I've also won 20, 50, and 100 donuts. You should try to find iTunes cards on sale. There will probably will be some more sales for Back to School (if your in America). Buy the cheaper amounts of donuts that you feel comfortable with and wait for the Gil sale. As it is, I'm about to go get the iTunes cards they have on sale this week and hope Gil comes with a sale in time for Krustyland. :D