If you are talking about reagents for etching metallurgical samples, then I can only recommend that you get the "recipe" for the particular etchant that you want and approach an analytical chemistry laboratory to mix this for you. This is the way that we always do it in our (small) metlab at work.

Being part of a large company that has its own analytical chemistry laboratory obviously makes it easier for us, but you should have such a lab. somewhere in your area that would be willing to help.

Regards
Niekie