I think That we are forgeting that the kilt is just one piece. So it is Cheaper than a suit.Then you have to buy a jacket to go with it the kilt So I don't think the difference in the end would be that much.

You have to compare like for like. If you buy an Expensive tailored suit you'll be in many cases using it for something special. So to get a fair comparison of the prices you'll have to price the suit against ..say a formal day outfit .