I'm looking for a decent used bass for my 12 year old son who is just starting out. I've found the following Ibanez in my price range: a 1993 SR500, a 2000 SR640, and a 1991 SR800. The 500 and the 640 are the same price, but the 640 is was purchased new 4 months ago. The 800 is $50 more than the other two, but might need some setup work. What are the basic differences between the three and is one considerably better than the others? I know that some of you guys don't like Ibanez, but for it's intended purpose, it's more than good enough. Thanks for your input!