i've used
halfords (bidston moss one) in the past just for a basic gear set-up and they managed to charge me £35 for the privilege of messing everything up more than it already was, which was annoying.
offtherock cycles in wallasey are good lads, more suited to mountain bikes i think though, but they get the job done promptly and at a good price.
Birkenhead Cycles i've heard are good, but i haven't used them so can't comment.
i've just got my new bike from
cyclehouse/cheshire oaks cycles and took it in the other week for it's 6-8 week service and they were brilliant, but i can't comment on their prices, my service was the free one.
Evans Cycles i've also heard very good things about, they're who i'll be using in future.
Here's their price lists CLICKY 
