Does that one have the ATI X1600 dedicated graphics? The graphics chip makes a huge difference to the price. I'd say R6500-R7000 max would be fair since that Macbook Pro must be around 3 years old now.
To give you an idea I have 2 Macbooks that I am selling. A Black 13.3 inch 2.4Ghz C2Duo, 250GB HDD, 3GB RAM for R6500 with OS X snow leopard and a 13.3" White C2Duo 2.1GHZ, 120GB HDD, 3GB RAM for R6000.
So judging from these specs I think R7000 is pushing it but depending on the graphics card.
I've got the same MBP 1,1 with 120GB hard drive and 2GB ram, looking to sell it as soon as my set of screws arrive from the UK! Yeah, I took it apart to to see how she'll run with a 320GB 7200rpm hdd & lost all the freakin screws when we moved!
So yeah, thanks for the price indication & watch the classifieds in a while if interested...