Help me to swap out six mushromm buttons with illuminated pushbuttons

I've gotten some very useful process visibility focusing on efficiency  and equipment utilization (and have gotten to learn python :D ). we'll be deploying 50+ LabJack U3's this year I have a question that (like many of my questions) many of you may find trivial ... I'd like to swap out six mushromm buttons per line (connected to the LJ) with illuminated pushbuttons (24v). I assume a relay to a digital i/o is the way to do this. Would some recommend relay specs for this? Is there a source better than Automation Direct and Famaga?