Last Thursday (so they may still be around) I bought a floor mat from Aldi. It's something like mouse mat material wise and has 1.25" squares in Black and White with am embossed finish.
Unfortunately the mat is printed on the diagonal so no real use as it is but five minutes with a scalpel gave me a variety of rooms and corridors to cover a pretty decent area all for £ 4.99.
Space Orks were the only thing around when I took the snap (they were waiting for basing on the work bench) - but Fantasy is the correct forum I think.