I think jockeys should be available at the market for purchase, or to bid on, but also I feel players should have the option to shell out money to scout for potential jockeys not on the market. Every scouting trip will yield 3-7 potential jockeys with varying skill. Just an idea.
Here you can also shop for available horses, and perhaps for less money, you can take a chance on breeding. So you could get an offspring for cheap, spend a year building it, and then race it the following year onward. What do you think?