As per attached, I have a 30 year old Efel Symphony natural gas stove. It still is working well. What I don't like about it is the fact that it has a manual gas valve along with a millivolt ignition. What I want instead is a gas valve/electronic ignition controllable via a WiFi wall stat. My guess is that such an upgrade would cost about $1,000.00. Can anyone assure me that it would be worth it to do? As I see it, if I did do the upgrade, there would be nothing left to fail. Another question. If I were to sell it locally as is, bearing in mind that new 40,000 BTU makes easily cost $4,000.00, how much could I expect to get for it?