I might not indeed understand your purpuse at the first time. With Sumo competition, you can use only one sensor to detect black or while edge. You can borrow it from LEGO stuff which they have a lot available.
But you said that IR array for line-follower does not need sophisticated control is absolutely wrong. It is only simle for very simple scenario and low qualified competition where you do not need to adjust speed of robots, control robot to follow complicated line, opening and closing gate, passing turnel, going down stair... and something more. If you do that, you need very good imput of IR array so you need to apply your mathematical knowledge somewhere as I told about Lagrange Polynominal. You can go to robocup.dtu.dk to see how much is different from competitions you have seen.
Cheers,