they will probably give you store credit. My brother sold his DS there a couple of months ago and they gave him credit. I' not sure about the .99 cent thing where you get 'actual' money. If you can't then you could always sell the credits on eBay or something like that.
The 99 cent thing hasn't worked to my knowledge for years the store credit is just that . Some stores give you the option of cash/check in the mail but usually at a huge loss and since you are not gonna get much for your psp anyways why didn't you just sell the thing on craigslist or something.