Do any ski schools subsidize exams?
The way they do it is by providing clinics for instructors who are not otherwise teaching. Some ski schools allow the instructor who is in the clinic to remain on the clock.
They also provide "In House" exams, but I don't think that applies to L3 or above, I could be wrong.
I was fortunate in that, the ski school I worked for provided free clinics while I was on the clock and the In House exam was covered.
The funny thing was, it was a bad snow year so lessons weren't plentiful, which meant I got a lot of clinic time, and I also got to shadow senior instructors in lessons a lot. That is when I found out I was better at the gear thing than the teaching thing. While shadowing senior instructors I made boot adjustments for students, recommended different pole lengths for students, recommended different skis based on what they could/couldn't do in the class.
One instructor told me THAT is what we're missing. We need a person to sort out some of the things about gear that instructors often miss.
Example: The student can't make a turn because she's in boots 3 sizes too big. Or, the student can't get out of the back seat because she's pole planting with poles that are 4 inches too long. Or she can't make a turn because she's 95 lbs and she's skiing on her husband's old SL skis.