Tutoring for tests with limited consumers is all about being able to attract clients. This isn't like the SAT where nearly every single HS student is taking it at least once. You have a very limited consumer base.. just those in medical school and even then, just those looking for additional help.
Test scores are among the worst ways to evaluate a tutor's abilities. Yes, it's important because you need to know the tutor knows his stuff.. but what's way more important is his ability to actually teach. That being said, it's way easier to sell yourself to clients when you have an elite score (it alone just doesn't mean you're qualified to tutor though). Considering that's the hardest part of the game, that usually weeds most people out. For instance, would you have considered a tutor with a score of 245? Would you have believed enough in the strength of the score to evaluate their other related skills? Don't know the answer to either question. How about when you change that to a 270?
I think if your pitch will be "I only charge $50 an hour vs. $200 an hour", it's not going to work out. There's not enough of a consumer base that people will opt to go cheap. If you needed tutoring to do well on Step 1 so badly, you're going to spend the extra money.. especially considering this isn't a test you can basically just try again like the SAT and (to a lesser extent) MCAT.
Do you have teaching experience? How do you plan on attracting clients? Where will you be doing so (how big is your medical school/are there other schools around)? There's a lot more involved than simply declaring yourself a Step 1 tutor.
I think tutoring becomes much, much harder as you advance from SAT --> MCAT --> Step 1 because the consumer base shrinks and it's hard to really sell yourself without showing you're capable of improving scores on each specific test.. and finding that guinea pig is the hard part as tests become more and more important.
IMO, if you're keen on tutoring to make some extra money.. try the SAT or MCAT.. or just college level/med-school level sciences.