Fencer - if the starting points and bonus are not to become unbalanced, could the option for starting points be a drop down menu where you can only select - for example - 1,000, 2,000, 3,000 up to 20,000, and once you have selected this figure - the option for bonus points is dependent on your starting figure.
For example, if you chose 20,000 starting, the maximum bonus is 500. If you chose 10,000 starting, the maximum bonus you can chose would be 250 and so on.?