We bought ours when we lived in Cornwall in an auction to clear a strawberry farm which was advertised in the local papers by the local auctioneers. The ones that were still standing ( with shredded covers) went for more than we could afford, so I bid (much to MoH's horror) on a huge pile of bits on the floor.
It cost me more to get it back home even with MoH helping load up, but we made-up 3 big fruit cages with the bits in Cornwall; a polytunnel and a fruit cage here in France (we had to buy a couple of NEW straight bits) and we've still got a few bendy bits left.................. So, it's well worth looking at local closing-down auctions..........
Oh, and there are some on ebay occasionally to dismantle.