Well, Puntz, using your figures, the cost of winning $155 at those prices for the second race would be $911 (rounded on UniTab). Still a lot to (maybe) win $155.

Leaving out the fav. (which didn't win) it would have been an outlay of $76 (rounded on UniTab). This is, of course, a much better proposition; but, if one of the two had not won, then you would have been seeking $231 with your next bet to win overall $100. When do you stop ???