LOL. Well, some 5 years ago, there was this OGR thread discussing how to drive the 3-aspect we_honest signals. We_honest offered their signal controller board as described earlier. The thread showed how to roll your own circuit for $1 or so in components with the timed-yellow. The same circuit could drive the 3-LED RYG or the 7-LED PRR style.
GRJ has already shown how to roll-your-own insulated-rail trigger (his so-called ITSD) in various threads. So the two circuits in combination could provide a low-cost (less than $5 in parts) option. No daisy-chaining capability, no clever bi-directional operation, no crossing-gate flashing, just basic drive-the-$4 3-aspect signal. End-of-story! 
