If you really want to see what high priced ammunition can do for you, first figure out how much you're willing to spend on a box of ammo, if you were going to stock up.
Then, call you're favorite distributor and find out how many lot numbers they have in the ammo that falls in your price range. Depending on how many lot numbers there are, order a box or 2 of each lot number and figure out which shoots best. When you arrive at that conclusion, order as much of that brand and lot number as you can afford.
I'd do my testing over a span of time and if possible, in differing weather conditions. Shooting precision rimfire matches can have you tearing your hair out.
In the end, what you're gonna be paying for is consistency.