Right now, WP Questions has:
$27,040 paid out as prizes
1630 questions completed
So the average prize so far is $16.59.
We have had a $4 minimum, but the majority of questions are well above that amount.
It is usually new members who ask questions for $4, and we want more new askers to give the site a try, therefore, we are dropping the minimum prize to $1. We figure we might as well make it easy for people to give the site a try, as we are confident they will come back and spend higher amounts later.