Setting it up is cheap. Planning it properly, and maintaining it properly for the next few decades is the truly expensive part, at least where I ride. Our local authorities cannot skimp on the (mandatory) design/planning stages, so they cut down on every bit of maintenance they can legally get away with. Sub-par plowing in winter, for example. Things are slowly improving, but it takes a continous political push. It helps that we have utility cyclists/commuters accross the whole political spectrum.

--J