Any of the I-Image machines (on the first or only head) you can easily replace the head yourself. Reason being, that first one locks into the exact position it needs. No calibration. No alignment. Just a couple small screws. It’s when you have a 2nd and 3rd head that needs careful alignment and a bigger challenge to remove old and replace.
As far as where to get the heads, I have no idea. People do or have bought the cheaper heads I’ve read, but know tho, as such, you get no support from M&R for that. Also if it’s a dif head during the first year warranty then it voids the warranty.
Maybe it might help to feel happier that you won’t need a tech on this and saving another 1000-1500 there. You may also consider…
A, you buy from another place at lower cost but no support.
B, you buy from another source that may down the road prove to be less quality and M&R ends up needing to fly a tech in to repair other parts costing 2-4 X what that print head cost.
Just a thought. May never happen but then again, could.