Do all blenders have the problem of food sticking to the side away from the spinning blades? We have a fairly cheap (50$) blender and when we puree food the food constantly sticks to the sides so we have to stop the blender 10 times to push the food back down so that the blades hit it. Is this common, or would a nicer/more expensive blender solve this problem?
In short, if you have enough liquid then a good blender shouldn't get stuck and you shouldn't have to scrape it down.  Read the answers to my question here - Blender Buying - Square vs. Round Container - that basically addresses the same thing.

Go for a square, glass container with ridges.