Couple issues...
1) is it 1MOA or 1.75MOA with "match ammo" (and what ammo is that specifically)? I only ask because there's a big difference between a rifle shooting 1MOA and nearly 2x that. 3MOA with your average surplus ball is about right...2-3MOA is probably about average.
2) how much money does he want for said M1A, what's the round count, how many mags, what accessories if any are included with the sale, etc.?
3) in addition to the amount you'll spend on the rifle, how much are you willing to spend on getting this rifle to shoot a consistent MOA?
I only ask because while M1As can be phenomenal rifles, including highly accurate rifles, it costs a fair bit to get them into that condition and often times, you can achieve better results for far cheaper going with a different platform.
Now, with that said...
1) trigger job (~$50 or so depending on who does the work...maybe a bit more depending);
2) unitized gas system (~$200);
3) NM Op Rod Spring Guide (~$45);
4) NM Gas Piston (~$30).
Those are a couple things you can get into without having to sell the farm to pay for them. You can also get into bedding your existing stock (depending on which one you have now, may or may not be worth doing) or into some of the M1A "chassis" system stocks as well (but that will really start driving the costs UP)! Don't forget, depending on whether you are planning on running irons or an optic, you will need to budget for those items as well. NM Front and rear sights will run you at least a few hundred more dollars for quality sights...about the same for a quality mount (Sadlak, etc.).