This depends on a lot of things, but you probably shouldn't go for a top of the line boot, you will be buying much more boot than you need which can cause more problems than it solves as you are learning to skate - a good boot should be supportive but not restrictive, and until you know you have the strength for very stiff boots they aren't recommended. A good mid-level boot is really where you should probably start looking, and as an adult skater you can definitely look beyond "beginning" boot models (which are typically aimed at much smaller and lighter children), but don't look much beyond low to mid level freestyle level boots.
Fit is just as important as buying a boot appropriate for your level... a boot that is too wide or too narrow or too long will cause a number of problems as well.