there's not a lot of difference in money between the cheap $500 stallion and a quality one with a $2500 stud fee.

That is true. Breeding to the $500.00 stallion verses breeding to the $2500.00 stallion could very well make the difference between the foal ending up on a truck to Mexico or having a decent shot at a good life.

As a responsible breeder, breeding for breed improvement, I don't mind paying the higher stud fee, for
the better quality stallion. I know there are exceptions out there, but they are very few, and I don't mind taking advantage of those either.