Equipment for Wench

I’m currently trying to get the equipment to make the Captain’s Wench. So far I only got a cable clamp. I found the grippers, but they are circular, and I would like to get rectangular ones. The Velcro I found was 15 ft long and costs $26. I also went to many stores and asked for nylon strap, but no one seems t know what it is.

Can someone tell me where I could get some of these supplies? I live in eastern PA if that helps narrow down possible stores.