It depends what kind of shocker you are looking for, an SFT, a PL SFT, NXT or NXT PL. But some SFT's go for around the £200 mark, some PL NXT's go for £600, so there is a big difference, decide what particular model you want and then go from there.
I just got an 05 dynasty shocker, with virtue board ccm frame and loads of hybrid upps for £220 posted. So you can get a bargin just have to keep your eyes open