Maybe a good laptop with some good software & VST fx connected to a midi/usb foot controller? Would probably be dearer than most fx boards when you include the cost of a reliable solid lappy, the daw & VSTis, the interface & the controller, but latency shouldn't be an issue with today's technology & you could make patches, link it to the band for syncing & even make fully evolving soundscapes.
But, would it sound as good as stompboxes???