partypooper, the bet or no bet part is totally up to you as it depends on what system/approach your taking with your selections and whether they meet your criteria that provides an ongoing profit.

How many races in a row do you think you'll need? I'd assume that by the time you reach the 5th race your stakes will be getting pretty high.

Also how do you progressively increase your desired profit? I just assumed that you increased it by $20 each race however you may double it each race, i.e. $20, $40, $80, $160 etc etc although doing it this way will just increase your staking even further.

I'll see if I can do something up for you and post it here, then you can have a play with it.