There are no Auction Houses, you do all your selling from your room. You buy from Brokers or by going to the seller's room.
Every village has 4 Crafting Societies, you should join the Wholesaler first, it looks like a trapdoor. Just speak to the person outside to join.
You can sell crafted items to make money or do collection quests for your Society.
You won't be able to afford a room when you first start, but not paying just means you can't get in until you pay.
Oh and there's always /auction to buy and sell stuff too.