I don’t think you’ll find anything worth while on Amazon. However, if you want a nice leather sling, I suggest checking out Etsy. A lot of great leatherworkers have shops on there that do nice custom leather slings.

If you are willing to go with non-leather, you can get a Ruger rifle sling on Amazon that is pretty nice.

https://www.amazon.com/dp/B019KATFS8/ref=cm_sw_r_cp_api_glc_fabc_pTN6FbC9SKXWH