The Barenia leather deploy strap from Omega ages really well and stays supple.
You can always add the distressed look later via scotch pad, fine grit sandpaper, alcohol swabs, antique finish, razor blade, etc. And the Omega barenia deploy strap is very affordable, especially compared to other OEM Omega options.
If you'd rather have a distressed traditional tang strap done by the maker Rover Haven does a really good job, and the seller jankoxxx on this here forum has made some nice looking pieces as well. Heuerville makes amazing pieces but takes a pretty long time. Panatime has a pretty large selection, but I'm not sure about quality.
If you have a single strap in mind then some pics could help.