The chemicals are not as bad as one might think.The echant comes as a dry chemical (ferric cholride) you mix with water...rubber gloves and eye protection. Once you make your initial investment you'll be able to make as many as you want. The comsumables are cheap enough, its the time spent doing the artwork that makes it expensive to have someone else make the master.
I found starter kits for as little as $70 and higher as you add the bells and whistles.
The question is how much are you willing to spend for a custom one time only decal sheet or PE fret? If someone was to product them...the only way the costs could be made reasonable is the subject being desired by others so it could be marketed to them as well.