Greetings...
After reading up on various options, I purchased a Samson Stage 5 Wireless vocal headset system for $95. I just received it- here are my first impressions (I have not yet tried it):

NICE!

It is very nicely packaged. Although not shown or mentioned on most web sites that sell it, this thing comes in a nice hard plastic carrying case, with foam inserts that all the pieces fit into.

Although the receiver and transmitter boxes are plastic, they appear to be well made/ well engineered (no gaps or mismatched edges). The labeling and lettering is good. The documentation is well written and printed (it says the thing is designed and engineered in the USA, of course, made in China).

The headset microphone and boom seem to be much sturdier than the Radio Shack headset (there is stiffer/thicker metal in the boom and the mike cover on the Samson mike).

The mini plug end of the mike cable has a screw on portion, that can screw onto the receptacle on the belt pack (keeps mike cable from pulling out). Another un-advertised touch (although I did see on one web site a "locking" version of this setup and a non-locking version. I didn't see any choice on most web sites, and the one I purchased never mentioned locking).

Two LED meters on the front of the base portion for checking signal levels-- good to spot from across a room (well, not a huge room).

Overall, I am so far impressed by the quality appearance of this thing. It looks like it is designed well and should hold up well. It could be a great value for the price.

I will test it this weekend (with a Yamaha StagePas 300 system) and post more info on the performance.

One thing I didn't realize till after I bought it: there is a Stage 55 version of these wireless mikes, that utilize technology called "diversity". They have two antennas instead of one, and can automatically lock onto the strongest signal. I believe this version was $165 v. $95 for the non-diversity, but this relatively small difference could be worth it. Most sellers also offer a choice of frequencies at purchase time (the manual states that the base and belt pack devices are "set at the factory" to matching frequencies, which makes me wonder if there is something inside the units that can be adjusted to changed frequencies... I seriously doubt they are using crystals any more, or that they manufacture 10 different versions. I may get crazy and open up one of the boxes to look).

I use this model. No problems at all. It is loud, I keep the volume control on the unit fairly low and use the controls on the PA. Just keep spare 9v batteries on hand. They need to be changed every few shows depending on long your show is.

I hooked it up, and it worked swell (gee!)...

Solid clip on the back of the transmitter- it's not likely to fall off. A slide button on top to "mute" the audio. LED battery life indicators on top of the transmitter too.

Thumbs up.