Hi sharp21.
I'm in the same boat with you right now, about to take the plunge and try service rifle this year at Borden. I too will be using the M14 for my first year, knowing all the pros and cons. The cost of ammo will be a factor, but for one year I can swing it and plan to collect the brass when I can and try my hand at reloading starting next winter.
Just got my RPal, but it won't be ready for this spring, so I plan to wait until next winter to even entertain the idea of an AR15 or similar for service rifle, and even then it will depend on how much I enjoy the M14 in these events.
I plan to shoot it with irons for a few sessions before scoping it, and plan on being equipped with a 1.5-4x for my first service rifle attempt.
You won't find any M14 mags on EE because I will get them first if they come up!

I joke, and imagine I will drop the $ to buy as many 5/20's as I need when I purchase my rifle, which I intend to do before the end of this month.
I share your excitement to try this, and will keep track of what you post here regarding your setup. I hope to see you on the range someday, will be easy to spot the guys with the .308's!
Good luck.