I wouldn't splash out on Finale match .... Nothing wrong with them, but you won't see any difference in the results you get between them and Match Kulgen.
RWS R10s are another good make and cheaper than Finale match.
That said, unless you are shooting thousands of pellets a week the costs don't add up to much.
As for size, most people settle for 4.49 - your gun may be different. I know a few top shooters, most of whom will admit to not seing any difference on the target between pellet sizes; so why not start there and see how you get on.
McT