I just got an email from Apple yesterday that they are coming out with a new iPod Touch with a 5mp camera & retina display. I'll bet you will see better deals on the older iPod Touch models after the new one gets released. Otherwise, there aren't many deals on Apple products. You could also try the Apple Refurb store - the products usually look as good as new, and come with the same warranty as a new product, but with a bit of a discount.
Can't help with the DSi's, though...
Good luck!