In a noisy environment, a lapel mic will pick up as much of everybody else as your own voice. I've also tried a lapel radio mic with a small PA in a quiet environment and got very little amplification without feedback problems, and even if you get some volume you won't get clarity.

I don't think the RS radio mic idea is very legal, and as for quality it's about good enough to use as a baby alarm (if you can still get them)

Proper VHF and UHF radio mics are expensive, but something like the Sennheiser EW100G2 range is worth every penny if you're using it (semi) professionally. Mary H has used hers (headset version) on festival stages in several places now and lots of people come up afterwards and ask about it.

Anahata