Admission to the festival is only $7/adult and $4/students and seniors, so you can't beat that! The pageant is more expensive, and it varies depending on where you're seated and what day it is.
The open-air gallery of the festival isn't huge, you could see it in a couple of hours if you're pressed for time, or you could spend the whole day. You can also opt to go on a guided tour, or just wander around on your own. My family and I enjoyed the tour because we got to meet the artists and listen to them talk about their art. It's really amazing because the artists have to be juried into the show by a committee, and then they are judged throughout the festival to determine if they will be invited back. It's very competative, and the exhibits are quite impressive.
I wish I could share more pictures, but most of them are copyrighted.
In addition to browsing through the gallery, you can create some art of your own if you'd like. This is my husband making a print.
I regret that I wasn't able to see the Pageant of The Masters. Really regret! But I will definitely catch it next year. The sets and the people are designed to look exactly like famous paintings. But don't think "costume," think "artwork."