I have no idea but I assume it has to do with not wanting people to "open them instantly" since you can purchase every 6 hours.
My suggestion would be to lower the conversion rate as suggested above but also reduce the # of shards per purchase & then also condense the node into a single rotating one.
So for example, if, as noted above, Wat is 2125 for 5 shards, or 425/Shard.
And you can purchase a max of 20/day.
Drop the conversion rate down to say 200/Shard?
Then change the node to be a random rotation of Wat/Kam & make it 2 Shard each time for 400.
This way the overall cost is less in terms of GET-3, but its still a slow/steady rate of purchase instead of being able to spam 20/Day = 140/Week EACH which is more than you can get in any TB.
8/Day, 4 Each = 28/Week Max EACH.
Which is "closer" to what a guild gets & isn't so unreasonably expensive per shard.
That's just my thoughts.
