I bought an ecobee3 thermostat and attempted to install it only to find out that my current HVAC wiring is super super old and not compatible. The box has been opened, but the unit has not been powered on yet. Comes with a secondary room sensor so it'll read the temperature across the house as well.
Works with both iPhones and Android phones, even Amazon echo too.
These retail for $250, and I'm selling it at a loss for $200. PM me if interested.