PMP is about as cheap as you'll get. Not sure how much postage would be on top, but Stan Yeo does not overcharge on shipping. Take a look at the price of Easycoat too. If you don't need genuine profilm colours, you could save yourself a few quid.
I also meant to say that you can buy profilm in 1/2 metre lengths from Spire Models in Salisbury. His price is competitive (about £7.50 a metre). Be aware that Neil is only opening the shop on Wednesday to Saturday and that he closed early. Phone before making a trip...but it is well worth a trip now we have no other proper (old-school) model shops to visit.