The company is called 'Footprint' and they are sold exclusively on eBay. The strap below cost £14.99 + £1.99 postage and packing and I think represents great value for money.
If you contact the owner of Footprint he will be able to offer the leather in a range of colours and even the waxed thread that binds the leather can be offered in a different colour. I opted for black as I wanted to maintain the stealthy, discrete, street photography roots that is the Ricoh GR.
The strap is really well made and will last for years. The more you use it the more subtle the leather will become but even brand new it is very comfortable and I prefer it to the cord strap that came with the camera.
Also supplied is an industrial strength rubber ring that can be used to slide up and down the strap to allow a tighter fit on the wrist. It is a brilliant idea and it works well.
For me a strap like this makes using the Ricoh GR more comfortable and it looks great! At some point in the near future I am going to buy a brown leather / brown wax thread binding version of this wrist strap as I think that would look great too.
Footprint make lots of different types of straps from neck straps to wrist straps with different fastenings. Check out eBay and you will also see that they have a Flickr page showing off the many colour combinations and types of straps they do.