Good microphone for a photo booth

[DaOld Man]

I have a nephew getting married in June. He asked me if I could throw together a photo booth for the reception. I had a Pi model B laying around, so I thought why not.
I ordered a Pi Camera and it works pretty good for still photos.
Then his bride to be asked me if I could include the ability to use the photo booth to make short videos.
I bought a cheap audio USB adapter that works pretty good, since the Pi does not have an audio input for the mic.
The Pi works pretty good for videos now.
Im experimenting with  a old cheap desktop PC mic that doesnt pick up very well.
I was wondering what would be the best microphone to use for this setup?
I would like one that can pick up the talk pretty good, and be mounted close to the camera, so users dont have to hold the mic.
Of course I dont want something thats going to cost me an arm and a leg either.
Do I need two mics to mount left and right of the booth for true stereo?
Thanks! (Sorry if this is not the right forum for this sort of question.)