What do you class as bulk buy and why are you wanting to bulk buy,
If it's just to get it a bit cheaper than you would pay at events the disadvantages vastly outweigh any price savings.
Unless you're buying for a team that's all shooting the same make of gun it's really not worth it,
Advantage,
You save a bit of money.
Disadvantages,
You have to have it all delivered ( this will involve a pallet delivery ) or you collect it,
You then have to look after it, store it in a dry place of the correct temperature,
You have to carry it too and from the events you attend ( bring the boxes you don't use back home with you),
If the paint you've bought turns out to be not very good you're stuck with it, ( even the best paint brands can have bad batches ).
You're not supporting the venue/event organisers that you're playing at ( most are event/site paint only now for this very reason )
Advantages of buying from the site or event you're playing at,
You don't have to take delivery of a pallet of paint,
You don't have to store it,
You don't have to carry it to and from sites/events,
If you get a box of paint at an event/site that's bad or isn't quite working for your gun they will usually swap it, and you're not stuck with it and loads of of other boxes
of the same paint.