Buy bets pay differently on each number. After you pay the commission the Buy bet will get True Odds, which pay differently for each Point. If you understand True Odds and you understand commission, knowing what your bets are going to pay shouldn’t be hard.
You must pay a 5% commissions, or vigorish (vig) on the cost of the bet. The minimum amount of commission you can pay is a dollar. This means the minimum amount you can charge commission on is $20 because 5% of $20 is $1. For every $20 you bet you must pay $1 commission. If you bet $21, $22, $23… all the way up to $39, it would still cost $1. Once you get to $40 it would cost $2. From a $40 Buy through a $59 Buy it would cost $2. $60-$79 would cost $3. Once you got to $80 it would cost $4. Once you got to $100 it would cost $5. $120 would cost $6 and so forth. Once a Buy Bet wins you must pay the same amount of commission in order to keep the bet up to win again. You don’t have to pay commission a second time if you decide to take the bet down.
When you buy a Point, you are paying a 5% commission to change your payment from Place Bet Odds to True Odds. The difference from Place Bet Odds to True Odds when buying the 5, 6, 8 or 9 are so small that the 5% commission you are paying could lose you money. Seasoned players will only buy the 4 or 10.
It makes sense to buy the 4 or 10 once you decide to bet $20 or more on either one. It will cost you $1 to do so and you will profit more because of it. If you Place the 4 or 10 for $20 and it hits, it will pay $9 for every $5 or $36. If you decide to buy the 4 or 10 for $20 you will pay $1 commission. When it hits it will pay $2 for every $1 (True Odds) or $40. For the $1 in commission, you get paid an extra $4. When you want to Buy the 4 and 10 at the same time, the dealer will add up the total of the two bets to determine the commission. I.e. If you wanted to buy the 4 and 10 for $50 each you would think “I need to pay $2 for the 4 and another $2 for the 10” but you don’t think of them as separate bets. You have a total of $100 in action, which is $5 commission.