The cost of each unit is about five grand. But factor in the following:
1. The ever increasing number of cops injured or killed while deploying manual strips.
2. The lowering of Police Intervention Techniques (the dangerous PIT maneuver which can result in unnecessary death or injury not to mention the inherent damage associated with the pursuit vehicle which can result in thousands of dollars in damages.
3. Every patrol vehicle would not have to be initially equipped. Usually just one or two in each patrol sector (depending of course upon the size of the sector). The number can be increased each year as new vehicles are acquired and the units on the decommisioned vehicles can always be transferred to the new patrol vehicles until all patrol vehicles could be so equipped.
Then of course I think it's Michelin that's coming out with the new airless tire which makes any such system obsolete. Nevertheless, you're looking at years if not decades before this new invention really takes hold.