I would probably try your local hardware store or local glass cutting place. The glass cutting place will have plexiglass as well. Are the templates particularly curvy or just mostly straight? When I had custom glass tops cut for some of my furniture (with curved fronts) the glass place told me to provide a life-size paper template for them to use.
Or...do you have a friend that has a scroll saw? If so, perhaps just some MDF board from Home Depot or Lowes with the templates copied/pasted onto the board which could then be cut with the scroll saw? MDF is very stable.
Not sure which of the above options would be the most cost-effective.