You can try coat your own stuff , a small airbrush kit and some polyester based clear spray like used in the automotive trde , you might have to experiment with brands for best adherence
This allows you to soublimate yourself – clear glass flat sheet may be a problem to do well. I fiddled with sublimation a little whiel ago and had great success with this coating on lots of items – some flooring paint on resins worked ok too , so long as the coating is synthetic.
I just thought you may like to know or try this.