Thanks go to Arshia on Plot 85 for this post and tip-off.

Recently I  have contacted a gentleman (Doug) – who is selling more than 500  1.8m posts through Gumtree (In Dyce, Aberdeen) with the very attractive price ( 0,75p each). I personally got a few of these posts and I am planning to buy more over the next weekend.  I thought maybe plotters might be interested in this opportunity.
Doug said he can even deliver any (bulk) collective order with his own trailer or you can arrange collection from his place.
This is the link to his advert on Gumtree:
I have the seller’s contact details and can share it with you.  Email me for details arshiakhatir [at] yahoo.com
Arshia