I'm an embedded product designer with over 30yrs experience and I'd like to try my hand at an affordable & expandable HA / HVAC controller. I'd like to keep the MSRP in the $200 range.

The following is a rough draft of the hardware & peripherals, if I've missed something you'd like to see added (or even discarded) please comment.

PIC18F87J60 microcontroller with Ethernet

6 Relays (2 NC/NO, 4 NO, jumpers / labels for GP or HVAC RE2-7)
4Opto Inputs with interrupts
1RS485 or RS232 (RTS / CTS could be reassigned as a SW TX / RX)
1RS485 or XBee / XBee Pro (Zigbee?)
1 SPI (RTCC with battery backup, 128k EEPROM html, ajax)
1Ethernet 10/100
1433MHz RX
1433MHz TX
1LM35 temperature sensor (freeze sensor)

The yet unnamed suggestions? controller connects to your LAN and could be controlled by anything with a web browser.

When this kit is done I plan on doing a 433 / 315MHz temperature / humidity sender to replace the traditional thermostat on your wall.

I'm trying to gather options, ideas before starting the PCB artwork.

Having been in manufacturing, i doubt you can make a product and support it , get all the approvals for $200, i think you will find the RRP will have to be around $600 :)

4 realys
4 x 232 serial ports
1 x 485
1 x Ethernet
1 x 1 wire sensor buss ( temprature humidity digital keys etc)
4 x opto inputs

keep away from RX TX devices as this will only give you to much hassel, stick with ethernet and wifi

using arozona micro chips are find make sure you add the brown out circuit.

That will be a fantastic job.I have no experience about PCB design but really admire you!