My gut feeling guess based on "small team, 4 months" would be around $200k for the initial development + a single full time employee for the future for maintenance and improvements. Add opportunity costs on top for focusing on something that's not their core business.

(Assuming US salaries, benefits, taxes and any related costs such as office space, equipment etc.)

But I'm probably biased as I spent 4 years of my life building and running a company that built a cloud based CI service for iOS, so that others wouldn't have to..

>It took us about four months to implement the new infrastructure on top of Anka with a small team

Quite a lot I expect.