anyone got any ideas/sources?
spoke to one stockholder in the area, wanted £32 + VAT for 5 mtrs of RHS

which seems steep?

I've been to goodman steel services in reading a couple of times. prices are ok if you buy in reasonable bulk, they go up if you just want one length, etc.

if you go to the office though sometimes they'll do a cash deal, I got a length of rhs for a tenner. You can also raid their big skips, sometimes for free (try the end of the day when the office staff have gone home), sometimes they want a fiver/tenner.