Indy, what about a Laney LC15? I am sure that I have seen them for under £200.00.
I got him to try an LC15 in the shop, and he didn't like it AT ALL. Its a bit(VERY) weak at in-store volumes - i'm not sure how to show him how it'll sound at higher volumes.
Also, the LC15 isnt hand-wired, custom voiced, and with a built in attenuator... There's many advantages for going minimat over LC15 - also the LC15 would probably be too loud.
I gotta agree, the LC15 is good for what it is, especially when it's cranked, but I wouldn't compare it to a minimat.
You should look around for second hand cabs, you're bound to find something somewhere and cabs tend to go pretty cheap second hand.