Working on a project

I'm working on a project and I feel like I'm stuck at the moment. I'd promised my metalsmithing instructor that I'd make a dozen or so aprons for the studio at $15 each (including my sewing time). She wants the aprons to be black with turquoise or red straps. It sounds simple, right?

Somehow I'm making this a bit more complicated than perhaps it needs to be. Finding the fabric is fairly easy because she wants something like a black denim that isn't too stiff or heavy or that feels harsh. A 100% cotton bottomweight twill fabric will do nicely for the aprons: the fabric is soft and smooth to the touch, isn't too heavy, and is woven tightly enough to provide some fire protection. Since these aprons are for the studio they need to provide some protection against fire and this twill should do the trick.

The more difficult part is the straps. My instructor and the students want straps that are soft against the neck and not too stiff or crinkly or plasticky. I'd thought about using 1" wide cotton twill tape for the straps - well, the neck strap, at least - but the only red and turquoise twill tape I can find anywhere is 3/4" wide, which I think might be a bit too narrow. As well so far I can only find it online and I don't really want to pay extra for shipping as I'm trying to keep costs down.

I could buy 1" twill tape and dye it the right colours. But then the thought occurred to me today that the soft twill tape might be a bit too soft and flimsy for the waist straps. I'm not sure what would be the best choice  for those straps - maybe bias tape of some kind?

If you have any advice about what would work for the straps for these aprons that is soft on the neck and strong enough for the waist ties and is available in red and turquoise... and is fairly cheap, I'd love to hear it. I'm open to pretty much anything that would work.