What would be a usual and custonary finders fee to charge for
arranging for one company to provide customers to another? The
companies involved are Practice Wares, a dental supply company, and
Quixtar,(formerly called Amway in the USA.)   Quixtar would be
providing customers to Practice Wares. The dollar volume would
probably be in the six figure range per month. Would it be out of line
for me to request a small percentage of monthly sales on an ongoing
basis?  i.e.  2% of sales per month over $100,00. I don't want to
charge too much oe too little.

Finder's fees are generally 15%, but for an ongoing product like that,
I think I'd probably do something more like you're suggesting.
However, I think I'd probably change to more at the low end and less
at the high end.

Something like 3% for up to $100K and 2% for anything over that. And
maybe even a little bonus for you if sales exceed X million per year.

Oh....and 0.5% for me. :)