Max: About 500, on ebay if you get REALLY lucky.
Normally: 200 to 300.
Lowball: 5 bucks, also on ebay, and really not kidding. A slightly more likely low-end estimate would be 150 to 200.
All these prices subject to change, availability, and the general mood of the people on Ebay or your chosen market.
Did you get this for about 500? Does it come with extras? These will impact your price.
First, thank you. I purchased this late 2009 for $750 from Bestbuy. No extras. My Dad is actually looking at purchasing this from me and I said I would make him a good deal. That is why I asked for all of those prices. I think I might just give it to him for free as a nice gesture. I am getting an iPad 2 for school with a ZaggFolio (Keyboard Case) due to the fact that it is very light compared to this 8lb monster and this wouldn't be able to last a day of school. Thank you for your response. Have a nice day.