How much does it cost to build a mobile game with least graphics (For example - Airline Manger 2 game) for android and ios.
If you're looking for a ballpark estimate, see if you can find the creators of that game or a similar game and see what it cost them to build and how many people built and it how long it took.
If you want to get an estimate from an outsourced dev shop, you will likely need to build out a game design document. The GDD specifies what features there are in the game, the core game loops, the monetization, if it has social features (like Facebook Connect and invites), what types of animations and assets there are, if there are in-app purchases, if it has in-game ads, etc. All of those things determine what needs to get built out and how complicated the final product is.
A game can cost anywhere from your time (if you can do the art and coding yourself) to a few hundred dollars for a simple Flash game cloned by a Chinese or Indian outsourcing shop to millions of dollars. Cross-platform mobile games, even simple ones, tend to cost in the tens to hundreds of thousands of dollars depending on complexity.
I will also add that the app stores are crowded places and it's very hard to stand out. Lacking compelling original features, some way to get your game noticed (like being featured by Apple or a significant marketing budget for user acquisition), it's difficult to get users to find and download your game. And the live operations piece -- gathering data and analyzing it, optimizing the game's difficulty, adding new game content and features -- is important to being able to make money.