Other than the Olympia and the Arnold Classic for obvious reasons I think that the rest of the pro shows should have no prize money. Now, before everyone gets their panties in a bunch here are my thoughts. First I am not 100% sure that this is the best thing to do just some food for thought.
About 90% of the guys who enter these shows not only realize that they are not going to make the top 5, but also know that they are spending a sizable amount of income to be there. The are not entering these shows for the money. Most are doing it to qualify and the rest are doing it because they love what they do. Most pay their way and are not sponsored. Almost always the top guys who win are the sponsored guys anyway so even though they are making some money they are also looking to qualify first and are making a good income already.
The next thing to consider would be who would enter these shows if there was no money. Like I stated already there are plenty of guy who need to qualify so there would be no lack of competitors. Most of the top guys won't be there anyway since they have already qualified at the Olympia and AC. I think that instead of handing out prize money the promotors should pay for a certain amount of the expenses. Maybe hotel and food and plane tickets if possible for all of the competitors.