Where possible our timber is from FSC certified sources, and our hoarding sheets are also OSB made with FSC timber. The importance of this can't be over stated.
There are lots of cheap alternatives on the market, but be warned - working with timber and plywood imported without the proper certification can lead to prosecution! Yes - even you - as main contractor / customer could end up involved in legal proceedings.
We have even heard of chinese plywood even being faced with illegally sourced tropical hardwood from areas of natural beauty.
Be sure when buying your hoarding, ask to see the import details of all products. You are well within your rights to do so, protecting our environment is an absolute necessity.