Thing with shockers you dont get many shots per a bottle (1k max) as you would with other types of markers. With a good short trigger setup you should be able to fire pritty quick and only a few years ago they were thought to be the best marker out there (ok maybe more than a few years).
But yes for £150 you should get a full setup from everything from barrels/bottles/hopper/spears and everything else......just make sure its not a "turbo" board shocker, since there illigal in the UK. (Full auto I think it makes them)