The nice thing about the Wren is you can make it as cost effective or expensive as you wish.
If you want air start and no ECU just a fuel speed controller the option is there.
If you want a maual start with ECU, ie turn on the gas and starter motor yourself the option is there.
If you want a fully auto start with all the bells and whistles the option is there.
I have gone from a hand starter wand to a Fadec ECU and mounted starter with a bendix and this is fine for me I have complete control over the engine during start up, but no expensive gas and fuel valves and there is nothing more satisfiying than building it yourself.
just my 2 dhs worth!!!

Lee