Presumably some governmental authority. Some realtime bidding system would be nice, but that may or may not realistic. I think a realistic goal is that the prices should be set such that there's always 1-2 spots available in any given small area (say, one city block). If you have zero spots available, then the prices are too low and should be raised. If half the street is empty, the prices are too high and should be lowered. The prices will have to adjust based on time of day and day of week, etc.. It doesn't have to be be perfect to be much better than the system we have now.