I'm looking for something cheap too.... some kind of strip with no holes maybe, so they can be drilled as needed.
I often use copper clad PCB boards.
I bought 12X12 Single Sided & Double Sided 1 oz PCB material and use this.
I cut them to length/width sand the edges and drill holes where I need them.
You have the option of soldering nuts/screws to the copper foil.
You can also solder (on both sides) a piece of DS pcb to a PCB arm, at right angles, then mount things.
The fiberglass is strong and won't kink.