We operate a little differently from most guilds; you buy your seat once, and it's yours.
If you ever choose to leave, you can sell it to the highest bidder.

Guild wars are on the way, with Guild faction points (working title) to be won. Also three new guild buildings.
Selling the original 30 seats at 100,000 DEC each has given us more than we needed to max the guild, so there's a decent pile of DEC just waiting to upgrade those buildings as soon as they're available.
But that's in the near future. Right now, the guild offers a 15% bonus for DEC earned in battle, and an 8% discount on skins, potions and orbs. In a couple of days, when those last few scrolls land, that'll become a 20% bonus and a 10% discount, before dropping back to 15/8 at the start of next season.
We've had a seat open up, which I've bought from the original owner for 100,000 DEC; and am auctioning off to the highest bidder (with a reserve of 100,000 DEC).