My question is can this work simple by sending data to the serial and be transmitted through Wifi?
I just want to open a Serial and send data, without so much configuration..
No. WiFi is a network connection and not a serial channel. So you have to open a connection on the network to send a data stream.In this case WiFi is probably not the best choice. Provide more information about the needs you have on that communication (speed, distance, reliability, obstacles, etc.), maybe we can suggest alternatives.
The NodeMCU is at the lower end of that price point and has WiFi built in. Set one to host, the rest as clients. I think they can even do mesh networking between them.
Ok, Xbees are expensive if you want to use many, I need a solution with 2-5 euros for each wireless module...
Will it give reliable 200 m range