@NaomiSkarzinski Mustard or garlic is a must! That's the emulsification agent.

I think my current one is a two-speed Cuisinart with a deep U-shape. I want to say I paid $40 for it.

I use it a lot for making soups. For example, It makes kick ass lentil soup. I don't have to try to pour the hot lentils and chicken into another container, I just stick the blender into the pot and go to town for a couple of minutes. As long as there's garlic in there my lentil soup never separates even days later.