I can get a 1284p for about $8 US for a genuine chip. I get the 328p for about $3.50. Ordered a Chinese generic one for under $2 to test.
I've never had issues with Chiense boards though, so it's not really about saving money.
I can set up the 328p and add the 2 decoupling caps and it's good to go. No onboard LEDs to remove or onboard regulators or sub to suck down power. You can get a 328p down to a few nA during sleep with work, bu a few uA is easy.
The 1284p should be good for about 15mA in use and somewhere around a few uA sleeping. The MCP1700 3.3v regulators sleep at about 2uA max, so I might be able to run an ESP8266 from a 328p or 1284p hooked to a solar charged battery.
