with paint as cheap as it is, i see no real reason to do this - unless your local site supplies you with really really expensive pant and no white box option!
i went to THE FORUM BATTLE and bought 3 boxes and had 2 left i used the last box bout 3 weeks ago, stored in the spare room rotated every 2 days, shot fine and no probs realy
You really don't want to know what that Your_MUM keeps in his cupboard
Seriously thought Robert, most walk-on sites sell paint for 30 - 35 a case and sup air sites/tourney from £25, the advantage is if it is crap you can take it back, kick off and get another box. If it's your own paint you can't do that, you're just stuck with sh!te that flys any which way or turns to soup in your breech, and spend a very unhappy day. If you want to shoot it in your back garden then that amount of paint will make a hell of a mess, better to get some reballs, more expensive at first but you can reuse them and it works out much cheaper in the end! Why do you think Joy are so good?
I've had zap primers kept in varying heat conditions, never turned over in sealed bags for well over a year that has been in perfect form when used, no dimples and actually, no exaduration, seemed slightly more brittle than i had remembered it to be.
you could try warped paintball,they are the uk distributer for tomahawk paint so may be able to sort you out a good deal in bulk,but tbh as the guys above say dont think you would be saving alot,hope this helps