If you have a stick blender (which you should have, because they are cheap and useful), mayonnaise is incredibly easy to make. Vegan mayonnaise isn't much more difficult: soy milk works as an emulsifier, and can be boosted with a little dijon (which I put in normal mayo anyways, because it's good).

I'll use Kewpie mayo for things that want it, but otherwise: store bought mayo is kind of gross, isn't it?