An addition to this could be to have a base figure determined by taking the price away from a set amount,say 100 and then applying the above formula.

For example we take the first two numbers of the price and take it away from the said 100

A $2.50 favorite would convert to 35 which we take away from 100 which would leave our base bet of 75

A $5.00 favorite would convert to 50 taken away from 100 leaving a base bet of 50

Basicly youve got a higher base bet on your highest rated horses before applying Bhagwans formula.