Well, that and making up 70 circuit cards and boxes...
Yeah there is that :),
I'd knock up a PCB with a matrix of 7x10 tiny circuit boards and snap-off slots so you can just break off the boards. Probably $100 total cost then easy to build.
It depends on the physical layout of the setup, making 70 boards may be preferable to having 70 wires over the floor. Also the modular approach is easily scalable.
But either way it's simple, just need to know about the non-electronic/software issues to see what fits the application better.
@boffin
Using FFs needs 4 wires GND, PWR, CLK, and DATA but it's really just the digital equivelant of what you suggested with the 556s. Fewer components though.
Rob