Man, you must be rich. The cheapest I've seen a Diamond list for is $1000. Still interested? They have VERY different requirements than most pythons, you keep them almost like a colubrid.
How much snake experience do you have? These are very advanced snakes to try and keep, they have a thing called "diamond syndrom" which tends to kill a lot of them before age 3. I highly suggest you read our caresheet on diamond pythons...
http://www.eastbayvivarium.com/price...ythonlist.html (currently sold out, $1000)
http://www.reptilicusreptiles.com/htm/pythons.htm (currently none available)
http://www.centralcoastreptiles.com/babydiamond.htm (no price, must call)
http://www.a1pythons.com/febcurav1.htm ($1000)
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