Resale value of a 2nd generation iPod Touch?

I have an iPod touch (2nd gen.) and I was wondering how much I could sell it for used because it would hopefully put a dent in the cost of upgrading to the iPod 4. It's 8 gb, the screen is perfect (I put a screen protector on it the minute I got it) and it has a little bit of dirt that got trapped between the case and iPod, but nothing that can't be wiped off. I saw a website called gazelle.com for this kind of thing but they said that in perfect condition this would only be worth about $50, which I personally think is a ripoff since I bought it for $230. So how much could I sell it for?