No you don't. A new state trooper's base pay is about 65k. See here, bargaining unit 5A:
Salary and Compensation
The state police operate specialized units that enforce commercial vehicle laws, reconstruct accidents in the event of fatalities, investigate statewide crimes like gangs, drugs, human trafficking, etc, assist with patrolling towns that are too small to have a large force, investigate arsons for the state fire marshal, have a bomb squad, apprehend fugitives, protect the governor, operate ballistics labs and drug labs, investigate computer crimes, etc. Plus they're the murder police everywhere except Springfield and Boston, show up to help at major events where there may be riots, and patrol Devens and Logan Airport.
So yeah, we can get rid of the state police, but someone has to do all that stuff, and do you really think it would be more efficient and effective if all these functions were decentralized, even if we figured out who to distribute them to?
And for the reasons Mike said, it doesn't make any sense (nor would it be desirable) to have municipal PDs patrol the highways. They do that in other states, and the result is atrocious, revenue-motivated speed traps all over the place, and a lack of consistency in enforcement. At least with the MSP I know I'm not getting pulled over if I'm paying attention to my surroundings and keeping it under 75. And I know exactly what an MSP cruiser looks like.