Hi,  Get thee to the nearest Harbor Freight store (or the web site)
and but the one they sell.  It is the same as the $85 ones but costs
$40 for the 6-inch one.  They are often on sale for 1/2 price.
I have an 8" one that cost me about $24 - cheap at twice the price.

By the way, they have a nice little 4" one for about $17 sometimes.
Check it out.  Their stuff is not the best quality on the long run
but the mics seem to be okay.  I'm going to get a couple more to make
digital scales for the mill and lathe.

Regards
Craig Smith