There are 3 vendors that spell 1 craftable house. There is a vendor in Celestia Base Camp near the Crustacean Empire that sells the Celestial Observatory for I want to say 75,000 Gold? Something like that anyways. The 2nd one is the furniture crafting vendor (the first vendor on you left from going in through the main gate) in Northguard in Grizzleheim that sells the Watchtower Hall for about 60,000 gold. The 3rd in the vendor in Abbey Road in Avalon that sells the Wyrd House (forgot how much gold). Good luck on crafting! Megan Frostflame Level 100
There's one in Celestia Base Camp near Crustacean Empire, one in Northguard (he's the recipe vendor there), and one near the entrance of Saltmeadow Swamp. Be advised that these are not easily crafted, they are full of evil reagents and have at least one component that must be farmed for.