The point of exhibiting, really, is for the breeders to show their artwork. I personally know breeders whose monthly feed bill is over $2000.
While there is the occasion exception, one doesn't "buy" a highly competitve bird for exhibiting competitively, one makes them. Most top breeders hatch 100 or 200 chicks from their top matings in hopes of finding a single chick that might, might place highly in the better shows.
If one is interested in the fancy, the hobby of breeding and exhibiting fine birds, then plug into the network of the breed of your choice. Attend many of the top exhibitions in your region. Yes, there is the high cost of travel, food and motels. Really get to know those who exhibit in the breed(s) of your choosing. You'll find most folks are extremely friendly and open to talking about their birds.
Arrive early and watch the check in, the cooping in process and note the converstations that take place among groups of people. Watch the judge moving in the aisles. (the aisle the judge is working in with her/his clerk is blocked off to prevent disruption.
Be sure you understand the difference between shows, ie, small county fairs where all kind of birds are entered and the judges may not be licensed at all and the whole exhibit is largely to enjoy for both fair attendees and participants. But, an APA or ABA sanctioned show is whole 'nother universe. The latter are vastly different affairs, as is the stock shown, the judging and level of quality.
Buying a bird in hopes of being highly competitive is a pipe dream and that thought is best abandoned for the real life nature of this hobby.