This topic rates right up there with oil and tires. At first I was going to jump on this and make some type of a comment about buying a less expensive detector that does only a partial job, thus leaving you almost as unprotected as no detector at all so why bother. Then I thought, man am too tired to yet again cover this topic the way that is necessary to give a meaningful answer. But, in the end I've got to say something.
Less than top line detectors will indeed pickup most radar and some laser signals, but often don't give sufficient warning or warn you until after it is too late. The Adaptive detector is an example of a well appointed motorcycle detector that only provides half-ass(1) measurably lower protection. But, it is waterproof, glove friendly and small! It does everything but give you good protection.
Let's take another tact here. Do you sometimes ride in a way that a radar detector may save you from a ticket? Do you live in an area where the police have the edge on you with up-to-date radar equipment? If their equipment is better than your detector you are getting a ticket. Now, how much would that ticket be? Do you normally ride borderline? Say 48 in a 40? 65 in a 55? Does your speed wander into the real danger zone where you could well be 15 or more over? If you ride 15 over or more what would that ticket be? What about your insurance increase?
Here is my bizarre suggestion. Estimate what a 15 over ticket would cost and what the resulting insurance increase would cost over the next three to five years. Now start your own personal insurance policy. Pay into the policy what you can afford, but pay into it as often as you can, because you never know when that ticket may be coming. Save, save, save against that rainy day. At some point, count that money, how much you got? I expect that your 'insurance' balance of $500 won't pay 3-5 years of insurance increase, so save, save, save. Oh, but wait -- how much was that top quality radar detector? Well golly dang, it cost less than what you have in your insurance policy...
FWIW.
(1) sanitized offensive phrase to make this post more palatable to the Adaptive leaning riders