As spangley said.
I had one of the very straps you are after and sold it over here in the end but I sourced it from the states. (Think I sold mine to scooby tgi but I may be wrong.).
You gotta keep looking and be prepared to pay over the odds. The good news is that there is no/very little in the way of taxes to pay if you import as they weigh next to nothing.
-ChEf