Ok, going to gas sounds like more trouble than it's worth. It's the 15% nitro that make it expensive anyway.
I've had lots of grief trying to make the engine run reliably at a low idle... lots of nitro, on board glow, etc...
If a spark would also make starting easier, that sounds like the way to go.

Since I'm going to build the ignition myself, I only need the spark plug. Where can I find one that fits the same thread as my normal glow plugs ?