YouTuber Oldbess recently uploaded a video about this cool method. Generally completing the scenario "Deaths of Chromie" will allow you to pick up the item "Time-Lost Wallet" in excess. You can get it from just killing the mobs or actually completing the scenario in full. By then end you will have dozens of time lost wallets. Each wallet awards 50g AND a rare chance at getting the ]bronze proto-whelp[/U] pet. In the video, this spot was VERY hard for to pull off as it requires a high item level. With an 809 item level I struggled all throughout the scenario and could not make this spot profitable for the time invested. The good news is, if you can get it done, the gold you make will be entirely liquidated – the rewards are 50g raw for each wallet turn in. I suggest you watch it on Oldbess's channel for full details.
Unfortunately, Brady has not published any updates on their much-vaunted site. They did mention a cool "binder" that contains updates and unfortunately I purchased it. It's an empty binder with neat Warcraft photos on it. Cute, but hardly worth ten bucks. My E-mailed requests for information on how to get the updates (if there are any and I just missed them) have gone unanswered.
Items you buy from vendors can be resold on the auction house for a profit. The most common way of making gold this way is finding either vendors with limited supply items that you can only buy a set amount of a particular item from and then you have to wait a while before someone can buy more, or buy items from vendors located in locations that are far off. There are also vendors that will sell items for other currencies than gold. One more important thing to note is that you can sell very common easily available items on the AH as well. Like crafting materials from profession supply vendors that only cost a few copper or silver that can be resold on the AH for gold, and they actually have a decent sale rate.
The entire Jade Forst is our farming spot for this one. Literally, the entire Jade Forest. The Jade Forest is crawling with porqupines and if you have a mage character, each one of them has chance to drop the polymorph porqupine tome. Which is excellent, because these tomes have a selling point of 13,000g across the board. They are really easy to get, and noone really pays attention to these spots. Try it if you like, I was able to get 2 on video, and have already sold one of them.