First reflection points are easy to find: just have someone slide a mirror along the side wall until you can see your front speakers. Mark that spot and place absorbtion there.

Bass traps are easy and cheap to make. There are recipes on various websites for everything from cylindrical traps to flat ones than can stradle corners (where pressure builds up the most).

However, if you can come up with all those excuses to not use treatments, then I can't fight them all. The excuses win. Room treatments aren't for you.