Well, the only real reason Im doing this CMP ME-109 as electric is because a buddy has the H9 1.50 p-51 setup as electric with an e-flite Power 160 on 12s 5000. My saito 220 powered H9 1.50 P-51 was being left behind quite badly relative to his electric one. The 220 costs $450 or so depending on where you buy it. I thought if I could get an electric power system for that or less, then Id give it go. I did an E-conversion with the kyosho .40 Corsair and it flies very nicely with a huge 3 blade prop....so.......its not the first plane ive converted either.
Here's the component cost for this CMP ME-109

Turnigy 6364 230kv motor: $63
Turnigy 100amp HV esc: $100
Zippy-R 5s 4800 x 2: $99 each
The two batteries are run in series for a 10s 4800 setup

So, $362. A saito 180 can be bought for about that price....so...price wise its a wash. As such, I have to disagree with the arm and a leg cost comparison because it isnt at all. Now, sure, either wait 1 hour for the batts to be recharged using two charges(which I already own anyhow) or buy a 2nd set of batts to fly while the first set is charging....which I also did.
So, you can add $198 if you want to the cost, but, that isnt really part of it to get the plane in the air. $362 is what it'll take.
I do agree in the short term, glow is cheaper to have mutiple flights per day as it costs about $30 for a gallon of 30%. So a saito 180 with 1 gallon of fuel cost is $410, but you can fly several times in one day. However, that gallon wont last all that long and you might get 10-12 flights out of it depending on how well broken in the 180 is and how big a fuel tank is in the plane. Also keep in mind for the cost for the saito 180(or any glow motor) is that you have to break in the motor with at least 2 gallons of fuel before ever flying it(or you should anyhow). So, add another $50 to the cost since one would probably use 15% for the break-in period to keep costs down slightly. So, now we're at $460 for the glow motor option just to get the plane flight ready(not including whatever servo you use for it....so another $20)

So, as I illustrated, it doesnt cost that much to do an electric conversion compared to running a glow motor or gas motor if you know where to buy the stuff from. I can see, obviously, if someone were to buy FLightpower or TP batts, that it would be extremely cost prohibitive for most ppl since a comparable 5s 5000mah TP battery is about $250 each. But, using decent Zippy-R or Zippy-H batts, motor, and esc from Hobbycity considerably lowers the cost. An e-flite 160 costs $170 and a CC 110hv esc would cost about $279 so if you use the BIG name brand stuff, your gonna pay out the nose. But it doesnt have to be done that way and Ive used Turnigy motors/esc's in the past with no problems.

In any case, an electric powered CMP ME-109 is gonna fly A LOT faster then any glow or gas powered setup and fly for about the same amount of time....6-8 mins. I know my KMP ME-109 with a saito 180 in it and an 18oz tank can only fly 7mins before running out of fuel. I know as I had to run the tank dry and deadstick the plane in as the throttle servo linkage crapped out at full throttle.