Which FC and GNSS receiver would be good to start?

tell me how i can make a efficent drone with less cost

Efficient for what?

Matek H743 boards and M10Q GNSS with compass are a good starting point for running a fully capable autopilot.

MATEKSYS H743-WING V3 FLIGHT CONTROLLER - ANUBIS RC are you taking about this model and can u please tell good M10Q gps ?? is matek m10Q MATEKSYS M10Q-5883 GNSS & COMPASS - ANUBIS RC can i use this gps ???

I don’t know your requirements so I can’t tell if it will meet all your requirements.

Matek makes decent stuff.