In the case of remote microphones, it is true that you get what you pay for. I purchased a lower-end Audio Technica mic that worked, but it offered steady background static, frequent bursts of interference, and practically no controls. I returned it.
Then I purchased a much more expensive G2 series mic system from Sennheiser (from B&H, by the way), and my preliminary tests came back with crystal clear sound. The only problem I’ve had is that, out of the box, it’s a little hot for my camcorder. But I can adjust the volume, the frequency, and various other settings fairly easily. I haven’t quite decided on the optimal settings for my equipment, but I’ve come close.
I’m a bargain shopper. Sometimes, though, the best bargains cost the most money.