Hi,
The first variable you need is the match back book for your selections. The second variable translates that into the cost of placing the best by dividing that figure into 100.
So I would create a remember trigger to establish the match back book figure (called match_b_book). I would then create a variable (called Dutch_Price) initially as 0 in the constants and alter it in the remember trigger as a value of 100/match_b_book.
I would then have a backing trigger to fire only if the Dutch_Price was above a minimum figure.
larp