Step one: Go to bootfitter.
Step two: work with bootfitter and figure out what kind of boot will work well for your abilities and preferences. (shell fit, flex, size, etc.)
Step 3: Pay the bootfitter for the fitting fee (sometimes free, sometimes 20-30 bucks).
Step 4: Find one of his recommended boot styles online for cheap, used is fine.
Step 5: Purchase said boot, and get them punched/ground/molded at the same shop, by the same fitter.
Step 6: enjoy outrageous skiing comfort, and increased skiability.