I agree on strapworks.com. Good source of quality material.
I am dubious about rachet straps from Walmart, Harbor Freight, and the like. At least, some of the ones I've seen. I actually bought some to hold my kayaks on my truck. But you get what you pay for and I would NOT risk my life or backbone on the crappy cheap stuff, which have very low breaking-strength ratings and warnings against use where human injury might occur.