I am one of thoose coaches that coach for the love of the sport. The only thing I have ever wanted was to see the athlete improve, and to be thanked when those improvements materialize. I would never ask or expect a portion of a prize, and would even turn it down.
I would appreciate, however, a show of gratitude at the conclusion of the season, such as being taken to dinner. What I find even better is a gesture (such as dinner or movie tickets) that includes my girlfriend, who many times spent time alone while I was dedicating my time to helping you to reach your goals.
Then again, this guy sending you e-mails, giving you workouts, which he probably stole from one of the many books out there, and hooking up once a month, really deserves little more than a "tahnk you".
Have fun at the spa... with your girlfriend.