“The modern astrophysical concept that ascribes the sun’s energy to thermonuclear reactions deep in the solar interior is contradicted by nearly every observable aspect of the sun.” —Ralph E. Juergens
I don't recommend buying them used. My brother has bought three off of fleabay with NO luck. The touch screens on them go bad and people sell them. He got a steal at 50 bucks on the first one, only to find that the touch screen didn't work at all. Bought another and it worked for a week.
I bought mine new at GameStop for 110, since the DSi's have come out, they've dropped in price.