[Splat]

I was thinking it'd be cool to have some exchange system you could run with the ops where you can exchange common things for unobtainable things at a higher price. So if you give an op a stack of stone bricks they destroy it and give half a stack of cracked or mossy bricks. Give them a stack of cobble for 16 mossy cobble.

I was thinking something like:
4 stone bricks = 1 cracked stone brick.
4 stone bricks = 1 mossy stone brick.
4 stone bricks = 1 mossy cobble.
4 (or 2?) obsidian = 1 end stone.
1 gold/lapis/diamond block = 1 grass.
4 gold/lapis/diamond blocks = 1 mycelium (since you only need 1 piece to start it going).

That way the blocks stay rare but are no longer unobtainable. The op destroys the blocks they were given 'cus they were being paid into the 'bank', which only the ops can access. Obviously it relies on there being an op on at the time but people are on and off a lot so sooner or later you'll bump into one.
While I'd like to be able to access and use end stone, I think it should be kept expensive so people wanting to build houses and towers out if it really have to work for it (but saying that it took me ages to gather enough obsidian for my tower so demanding 4 times that amount is likely prohibitively expensive, so 2 is probably better. And since mycelium and grass automatically replicate infinitely once placed, I think it'd be fair to make them cost something valuable.