I just went to the car wreckers with a shifter and knife and unbolted what I needed at no charge.
The belts have no commercial value, on the stripped cars when they are ready to crush.
It took me about an hour to gather up a milk crate full of all sorts of belts buckles and clips.
Cut them to what you want, run the cigarette lighter over the cut end to prevent fraying and stitch them up.

I made up ankle straps that go through the mast brace to restrain the legs in an upset and used the belts for that as well. I stitched hook and loop velcro to the belts to make it a couple of second job to put the ankle straps on when getting in. I was worried that a leg over board during a "turtle" would result in injury.
They don't get in the way at all and have already proved they work.