Another Indy person looking for the last week of March. I've noticed the same thing. I always try and fly Southwest, but this year the fares opened up while we were out of town. By the time I got home and looked the Internet fares where gone, out of here! Now I'm looking at 400 to 500 dollars per person from Indy. Let's hope the current flights book up completely and the carriers will have to add more. Maybe a stretch to think that, but you never know.
By the way, April 1st - 3rd is Final Four weekend in Indy. Getting flights in and out of Indy the week prior and the week after will be difficult because of the number of people who attend the event. It will be crazy here, but well worth it in my opinion.