Cold rolled steel angle is what you are looking for and will only be found at local and online steel suppliers. It is formed into angles from flat strips and is normally found on steel shelving units (has punched holes in it) and in Uni-Strut. You can buy it at Lowes and Home Depot. The drawback is that it twists fairly easily. It looks like this.
You will be better off using the much stiffer hot rolled variety and sanding off the scale if you want to make bearing trucks.