You really have to ring around as 1) prices vary LOTS, 2) they're always open to negotiation and 3) the amount you buy has a HUGE effect on the opening price/how much bartering can achieve i.e. if you were to price the job based on numbers from the likes of say Welderpaul you'd probably be in for a shock as he's regularly buying tonnes of the stuff at a time and therefore gets much better rates than the little guy/random customer