Guild house

A guild house is a private hall on GM Island that only your guild can see. Every guild gets its own copy of the island, so nobody else's purchases show up in yours.

WhoTalamortis, the Guild House Seller
WhereAlong the auction house counter in Stormwind's Trade District and Orgrimmar's Valley of Strength, a few steps past the Warpweaver.
Cost1,000 gold, paid by the guild master.

Buying it

Only the guild master sees the option to buy, and a guild can own one house. Once it is bought, every member gets a teleport: talk to Talamortis, or type .guildhouse teleport (.gh teleport for short) anywhere.

A new house comes with a portal back to Stormwind or Orgrimmar, depending on your faction, and Xrispins, the Guild House Butler.

Furnishing it

Talk to Xrispins to buy things for the house. Any member can buy, and the gold comes from whoever is buying.

Class trainers100 gold each
City portals100 gold each
Banker100 gold
Auctioneer100 gold
Innkeeper100 gold
Profession trainers50 gold each
Vendors50 gold each
Mailbox50 gold
Spirit healer10 gold

If the butler goes missing, the guild master can type .gh butler inside the house to bring him back.

The guild master can also sell the house back to Talamortis. That clears out everything in it and refunds 500 gold, half the price of the house. Nothing comes back for the furnishings.