Just have someone buy a stun gun, take the circuitry out, put it in a $3 RadioShack project box, and send it to you. As soon as it's in a project box and not a stun gun housing, it's no longer a weapon; it's now a high-voltage step up circuit used to ignite propane.
I'll do it for $5 more than the stun gun costs

I can get 100kv stun guns for $17 with shipping, so that'd be $22 + shipping to you, probably a little under $30 total. You can also buy an ignition box from Gort, I think Pimpmann sells them too.
Peace,
Pete Zaria.