In order to minimize costs and maximize results, I would recommend a hybrid hydro system. A drip system for your orchids would be the most cost effective, while minimizing the stress involved with transplanting or media change. A drip system involves a nutrient reservoir, drip line, emitters and timers. It would be an easy addition to your current system, and prevent you from having to totally re-do your current set up.
The orchids will need to be organized by their lighting and water requirements. By attaching plants with similar light and water requirement to the same drip line, you simplify the system and prevent having to use a different timer for each plant. The water timer offered here will allow you to effectively manage the watering amount as well as the time between waterings. An emitter or inline drip system would be ideal, as you can alter the spacing between distribution spots.
Good luck with your orchids!