It depends. Is this ps2 a regular or a slimline?
If its a standard PS2 versions 1-3 then you are looking at around $150.00. The remaining revision of the standard PS2 you are looking between $150.00 - $200.00. A Slimline PS2 I have seen go for as much $250.00.
I know I have been looking recently for one. PM me with descriptions of what you are including as I may purchase from you.