Murray - Yes, if you go the "wireless" route it can get expensive quickly. This set, however, was cabled into the sound mixer, so, in theory, it was about as expensive as a Shure SM58. But it does raise the question of how much cable you can have before there's line loss ? This had a very short tether, but he was close to the sound board.
The "wireless" route would be ideal, but most sound gurus I've talked to prefer to be wired in - security (job security ?) -- less interference from Police calls, amateur radio operators, etc.
I agree, it would be ideal to have the mics hidden in the hair -- I saw a performance artist a few years ago who had that set up and it was great. However, since one of our band members is balding it might be a bit of a stretch !?!