Well, I was thinking...

Due to the fact a lot of the world structes and horses etc. have been raided and/or stolen it has been tough to find rare items that you'd find in dungeons or villages. e.g Spawners, discs, horse armour, saddles. I was thinking maybe the world should be extended by 500 blocks each way or something. I'm think this would be nice. c:

I believe that this was discussed here: http://sneyersul.eu/forums.php?t=13003

So, to expand border. You must pay.

Essentially, yes. Since we're running the hub, Creative, Skyblock, and Survival all at one on a set capacity; it's hard for us to maintain costs on memory. 

Therefore; to allow the effort to let us pay for more space, players can pay to add 1000 more blocks.

im kinda confused is it every time a player pays the world boarder get extended? Or is it if a player pays the WB gets extended for them?

It extends for everyone.