David O. Cooper, producer of Jack Houston's ImagineLand generously answered a question about purchasing microphones that was posted to the puppetry mailing list, PUPTCRIT.
I would suggest highly that you look into several of the headset mics that are available on the market by Shure, AKG, Sennheiser, Crown or Audio Technica. I would also recommend that you stay with a condenser mic as they usually maintain a better frequency response and stronger output. Cost is not always a good indicator of which mic may be best for your application, but I think you will end up spending somewhere between $125.00 - $275.00 on a decent mic. Only you know the requirements you need with respect to size and audio quality for your production.
The problem with a normal LAV I've found is that when the puppeteer moves their head from side to side there is a noticable change in the levels and tonality of the audio signal. Some people have made headbands to hold regular LAVs and other mics. But the headset mics are designed to keep the proximity and position of the mic constant and may save you some headaches making your own.
You will also probably end up modifying the windscreen used on whichever mic you choose. The mic placement sometimes needed by puppeteers often requires some ingeniously creative fabrications to eliminate popping noises and other rustling noises encountered in puppetry. One application we discovered that worked on Jack Houston's ImagineLand Show with the host Jack Houston who wears a cowboy hat was mounting a LAV in the center front brim area of the hat facing down towards his mouth. The surface of the LAV was flush with the brim of the hat and hidden behind the hat band to reduce both visually noticing the mic and phase problems with the hat itself. Since he never removed his hat on camera this effectively became his "Hat" headset.
Before buying a wireless mic . . . be sure to check out the venues you will be using it in!!!! Many of the cheaper wireless mics will experience all sorts of interference especially when around lots of electronics and other transmitters. The selection of frequencies used and the building environments you will be using the wireless mics in can be crucial factors in their performance characteristics. I've used both cheap and very expensive wireless mics and many times had to go back to a normally wired mic to avoid the interference problems which are not always consistent or predictable! Unless you absolutely need the wireless feature, I'd recommend getting the best wired mic you can afford. That way you'll be getting the best audio quality for the buck you can afford. Also, don't overlook borrowing or renting a mic you are considering buying to see how it will work in your situation before actually purchasing one. There are many rental firms around the country which rent LAV mics.
I hope some of this helps you . . . . best of luck with your purchase!
David O. Cooper, Producer
Jack Houston's ImagineLand
Brasswind Recording Studio