I spent much less on detectors over the last 20 yrs, than the tickets, insurance increases, and loss of license would have cost me. A NO BRAINER. Remember, detectors are not just for "speeders" Many times I have been saved by rolling through a town, at say 40 in a 35, and then there is a hlf hidden 25mph sign ahead, and the detector goes off while I am still in the 35 zone, but it alerts me of a speed trap set up at a crossover point. Most people SLOWLY reduce speed from a 35 to a 25 zone AFTER the 25 sign, but if a cop is shooting radar, you better slow down BEFORE the swithchover.
I have a zillion stories of how a detector has saved me, (I do 30,000 miles a year MINIMUM). All it takes is one 15 over ticket, and your detector would have been paid for.