Sampsons went a few years ago. Towards the end the chap there was making his money from printing and didn't have much actual camera gear in the shop.
In the city centre there is, afaik, only Jacobs, Jessops, John Lewis and Currys Digital who do new cameras. Currys Digital are quite poor though, and have very little stock. Outside the city centre there is Currys in Speke and Currys in Aintree. The Aintree branch has more cameras, but mostly compacts, but they are all out to try.
Back in the city centre there is Newton Ellis on Cheapside who repair cameras and deal in a bit of old gear. Been many years since I've been near there though. :shrug:
Can't think of anywhere else. :shrug: