I bought Ray's expedition raft rig and it obviously came with a bunch of his straps. Mostly the wider 1.5" straps and they are by far and away the best straps I've used. He uses material similar to seat belt strap, a really heavy duty buckle and sews a d-ring into them too. The D-ring really sets it apart since you can use them to keep the end of the strap from flapping and they are super useful for clipping stuff into the raft too.
Surprisingly, they are even cheaper then the equivalent NRS strap (6' 1.5" strap from NRS is $8.45 and Ray's are $8 flat).
For what its worth, considering some of the health issues he's gone through recently, its even more of a reason to give him some business. He is also a sponsor of Mountainbuzz.
1.5" Heavy Duty Cam Straps - Raft Rigging - Tuff River Stuff
Oh....and it says 2800lb rating too. Not that you'd ever load them up that much. He makes 1" straps and loop straps in both widths and many different lengths and will do custom lengths too.