I have a 2008 Marzocchi Roco Air 3PL shock that came with a frame I bought secondhand earlier this year. No good to me as the stroke is incorrect for the frame (200 x 57, should be 200 x 50). The main issue though is the rebound appears to be blown.

Given these retailed at £300 and a service is about £80 from Windwave is it worth trying to sell it?

even blown someone may need spare parts etc or be able to service it themselves

Somebody would have it.