Steel type & online suppliers

[Talonmotorsport]

Not all online stores are kept up to date and don't always list what you want or need. best thing to do is find a steel stockist near you and give them a bell they don't bite.
I would go for either 1.6 or 2mm ERW as it folded to shape has flat sides, squarer corners and it is much easier to work with than 'Hot Roll section'.
A few days ago I payed £8.38 plus VAT for 6m length with 1.6mm wall.

Hot Rolled Section or HRS/C is extruded and although cheaper will be at least 2.5-3mm thick have rounded sides and large radious corners. It all so comes covered in a black scale that needs to be removed before it's welded.

You pays your money and make your choices.