Cheap U-beams?

OK, it's not welding but it's metalwork and someone might know - I need to rebuild my old rotting timber patio and I thought of making it look nice and a bit different. An industrial look, with U-beams. Problem is, 90mm x 2.0mm SHS is about 1/3 the price of 150mm x 75mm U14 beams. Is this the norm? I hardly need the structural strength of a U-beam but I like the look. I could repurpose old gumtree beams but it might take a while to gather enough and the right sizes ...