Get on the Walsall Road out of Birmingham and head to Sporting Supplies ( Willenhall Lane, Bloxwich - 01922 406777 ), it's about 20 mins from city centre of Birmingham.
Best selection of airguns I've seen and pretty much the only shop that has a couple of ISP Spartans in stock. There's tons of shotguns, firearms, knives and clothing etc too.

( Have I made it too obvious that it's my mate's shop and my other mates work there? )

Craig