Jesus PD must love you guys, you're so easily suckered in. I don't understand all of these "It's only $10, that's nothing" and "It's only the cost of a few beers/coffees therefore it's not expensive" comments.
Those items cost that much. That is their price, so you pay that for them. The DLC being a similar price is irrelevant because it's a completely different market, a market where prices vary and you should buy things based on your desire for them, AND if you think it represents value for money.
Yes, it is "only" $10 and that isn't a lot of money in the grand scheme of things, but haven't you guys got any principles? Do you just thrown your money at anything? A lot of you seem to be saying the content is irrelevant, you're paying up simply because it's not much money and you want to "support" PD. You already did that paying for the game itself, making PD plenty of money.
The cost of other DLC in other games is also irrelevant. If you think they're overpriced, don't buy them either. But don't use those more expensive prices to justify the cost of the GT5 DLC.