I spoke to Matrix the other week, they reckon £6.95 (+vat i guess) for 0.5m wide 300g uni-d at the moment. That would come down if enough is bought and I'm looking at maybe 10m myself.
Could do with some weave or biax as well.. not much though, perhaps 3sqm. Again, if nobody's got any offcuts it might be worth seeing if bigger lengths can bring the cost down.