The email I received from them referred to it as an “agreement” or “commitment” “Unfortunately, there is no way to pull out of your fundraising commitment.

Practical advice, not legal advice. I am not an attorney.

It's very easy for their customer service reps to dispense the company line when all you're doing is playing email pong. You need to speak to a human being on the telephone. Take the approach of, "Gosh, I'm SO sorry about this, but I got injured early in my training period and I won't be able to run. Fortunately I was able to raise $200 which I'm SO happy to contribute." If they come back with, "Ma'am, unfortunately, there is no way to pull out of your fundraising agreement -- " immediately interrupt in the most cheerful, positive tone, "Yes, that's great, and it's why I'm SUPER excited I could raise $200 for you! Isn't that great?" You kinda hafta hit 'em with your inner Moronic Pollyanna. If you're able to establish rapport with the customer service agent -- or just stonewall them until they give up -- you have a reasonable chance of meeting with success. You might just reach someone with a brain who realizes it's easier to let you off the hook than risk any potential negative publicity which might follow if they stung you for $1800 you can't afford. For eighteen hundred bucks it's worth a shot. Worst case scenario is you wasted a phone call.