I guess nobody clicked thru to my link in the above post for the iRig Acoustic Stage which just came out last week,
For $99, looks like it solves lots of problems at once. But what do I know? I dont have one yet to speak from experience.
Having said that, using a wireless (likely hand-held vocal) mic into a guitar amp designed for 'electric guitar' is going to be lacking in both bass and treble frequencies, and quite heavy in the midrange, and sound quite harsh and brittle to the audience, bordering on sonic punishment of their ears.
Brad has a good plan.
You can even spend $5k, $10k or more on high-end mics and preamps, but unless you are getting paid big bucks or are independently wealthy, my guess is you are looking for something that most of us plebs can afford.
The KM184 is a good mic and so are Avalon preamps.
It might also be helpful to search this forum for the word 'impedance' and learn why this is an issue with both mics and pickups in the 285 search results of threads where this has been discussed previously. I am not typing it all out, again.