Plan on taking a few lessons over time as you can't expect any coach to tell you to change something and it becomes habit right away. Even small changes take time and practice before they are part of your memory. Lessons are a much better investment in your game than any new bowling ball can provide.
Both names you mentioned will be higher in cost than most other coaches but you should get what you pay for. I've found that those really good coaches saved me money in the long run as I developed much faster than with a cheaper but less qualified coach.
Make a commitment to practice in between lessons the recommended changes so as to maximize the effectiveness of your lessons. This will reduce how many lessons it takes to get each change integrated into your game.
Make sure to ask about mental training and lane reading once you've improved your physical game as those attributes become more important the better your physical game gets.
