The grid intertie inverters that I know about, limit what you can do. Most require a fairly high input voltage, meaning needing to buy more than two panels at a time to run in series. (Like 6 to 8 at a time.) Some that can run with two panels need to have a minimum sized battery bank to operate( Outback and some Xantrex inverters will work on a 24 volt system) The small Enphase inverters will work with a 24 volt panel or possibly two 12 volt panel. They don't match up well with many types of panels. They are designed for panels with 72 cells (24 volts nominal) and around 200 watts. The only metering available is online from the company and carries an annual fee. If you buy one large inverter to start it will take more than the $1000 you have just for that. So to do like you contemplate you should look at the Enphase inverter requirement closely and get solar panels that will work at that voltage and wattage. Then you could add panels and new small inverters each year.
You didn't ask about grid intertie requirements from the utiliy, costs of meters, permits, or inspections but you are going to have to learn more about that also.
Grid intertie seems simple but all the other pieces double the cost of the installation over just the cost of panels.
Chris