On the bottom is says: Payment fees are NOT included!
Average payment intervals computed for MY Masternodes only.
If I may, what are were your startup costs and how much do you cost to your nodes per month?
I'm not 100% sure if I understand your question correctly...startup costs for one Masternode are (obviously) 1000 DRK, and that costs are of course dependent on the exchange rate when they were bought.
I have some which were mined, but those were probably even more expensive due to electricity costs.
The payments fees (which are included in most transactions) are negligible, they are usually in the sub 0.001 DRK range and wouldn't make much of a difference.
The running costs per Masternode are about $3.5 per month.