What's a fair price for a bong?

So this kid wants to sell me a bong, but I've never used one, I don't even know how to use one, and I don't know how much a bong should cost. He said he bought it for $300 and it's almost brand new. And he said he'd let me pick a fare price. He said it's a "C.I.X. bong. Gl on gl with a shower head diffuser and a disc perc that acts as an ice catcher for the ice chamber. It has a long beaker bottom and it's very very rare." What does this mean and what's a good price for it?