Assuming there are a minimum of two teams a total of 20 maintaining this in-house software, I gave 250k as cost per engineer (salary plus health and other benefit costs to the company). Thats $5 million right there. I am estimating lowest range. Thats why Amazon calls these efforts undifferentiated heavy lifting. is there a slight premium to pay than rolling your own and maintaining yes. Its worth all the trouble and security and management overhead into rolling your own.