I wonder if anyone can give me an idea of the price of 3"x2" treated timber for external use. It would be used for the construction of a polytunnel and I think the total amount needed would be in the region of 130 feet.
I would also need about 50 feet of 2"x2" treated timber for external use for the doors.
Wickes is as good a place as any of get this for a DIYer. If you don't have one near you, try phoning Jewson or one of the other large Builders' Merchants near you to compare prices. Expect discount on this sort of quantity (though not from Wickes). You will find it priced per metre and sold in various sizes from 2.4m to 4.2m in 0.3m increments. You should be able to work out which length multiples you don't want - to avoid too much offcut waste when you cut.