​      I purchased the key from e-bay. It's a 2 position key (on/off) for motorcycles and it cost me $1.74 free shipping - here is the link. There are 5 position switches on the market but they are more expensive, so if you want more realism, you can purchase one of them. On desktop aviator page i found one for around $39. You can also find a 5 position rotary switch and use that as a key as well, it depends on you. I found Bat/Alt double switch and the Avionics switch both locally for 0.80 Euro. They both were red with  0 1 numbers written on them. I sanded a little bit and painted the Alt Bat switch red and the Avionics switch white. I purchased the rest of the switches from ebay (Fuel pump, Bacon, Land, Taxi, Nav, Strobe, Pitot heat). 10 pcs for $1.96 - free shipping here is the link.