Best suited Arduino compatible chip

I've completed my project using Arduino Nano on breadboard. Now I want to minimize all the hardware and cost for the project.

Guys, suggest me best and cheap Arduino compatible chip which supports 4-8 IO pins and serial communication.

Also it should consume less power.

Tiny 4313, 841, or 1634 Come to mind. The more common 84 and 85 don't have hardware serial, though you can use softwere serial.

How many copies of your device do you plan to make?

If you are only making a few I suggest that convenience should be the governing factor rather than price. Why not just use a 328 ?

…R

Atmega8, if your sketch fits.