Are you sure it was £70 for 2000 and not £70 for 1000?
£70 per 1000 is on a par for buying at smaller numbers of 100 to 500 at a time, and around £50 to £60 for 1000.
At a punter site £70 for 2000 would be a good price - maybe you did get that price as they are still getting a good price per unit, and as its the amount in a case have the minimum staff cost as all they have to do is pick up the box and hand it to you.
http://p8ntballer-forums.com/threads/what-paintball-costs.153010/
It seems a rip off when looking online, or when regular players pay walkon or event prices and forget what it was like when they began. Punter sites cater for the random public, only make money twice a week and most people don't turn up if the weathers dodgy.
Normal punter play is like nightclubs - you go once in a while with your mates, pay a premium, have high numbers of staff watching you and hope to get lucky
Getting a punter site membership/discount scheme is the same as going to the pub, you go more often with mates, pay a bit less but drinks still cost much more then wholesale,.
Walkons are like private clubs - you pay much less for drinks but club members run the committee etc, most walkons are started & organised by a player and use less staff resulting in low overheads on the walkon as the punters are still the basis of the site.
For paint quality punter sites want a basic tough paint that will survive in basic guns, shoot through bushes and give a high profit margin. The site doesn't realy know how much paint they will use, they must have plenty paint on a busy day and if people come with fat wallets, but don't want it to degrade fast if they end up with a cold quiet day and its going to sit in the store for weeks.
The elite professional tournament player wants a perfectly formed sphere, fresh from the manufacturer with just enough time to 'cure', and is so fragile that it will only just survive being shot out of the gun but then break on the softest target. You won't see that at £20 per case.
Normal people want something inbetween, 'better' and more fragile then punter paint, but the higher the quality the higher the cost. Mechanical guns will be too tough on fragile paint, a fine tuned tournament level gun with a bore matched barrel can take fragile paint but as long as it flies in the right direction and can break on a body then its good
See what other people are choosing at a walkon when you probably have 2 or 3 choices. At events you can have a wide variety of choices but if in doubt look at what other people are buying but see what sort of player they are, start at the mid price and ask the seller