The next World of Warcraft expansion, Battle for Azeroth, takes the game back to its roots a bit by focusing on the battle between the Horde and the Alliance. Each side will be able to explore three new zones. The Horde will have access to the islands of Zandalar while the Alliance will be able to traverse the island of Kul Tiras. These new areas will reportedly contain "allied races" which players will be able to recruit and eventually play as. 
Alpha Beta PTR Classic 1.1.0 1.2.0 1.3.0 1.4.0 1.5.0 1.6.0 1.6.1 1.7.0 1.8.0 1.8.4 1.9.0 1.10.0 1.11.0 1.12.0 Burning Crusade 2.0.1 2.0.3 2.0.4 2.1.0 2.1.2 2.2.0 2.3.0 2.4.0 2.4.3 Wrath of the Lich King 3.0.2 3.0.3 3.0.8 3.1.0 3.2.0 3.2.2 3.3.0 3.3.3 Cataclysm 4.0.1 4.0.3a 4.0.6 4.1.0 4.2.0 4.2.2 4.3.0 4.3.2 Mists of Pandaria 5.0.4 5.0.5 5.1.0 5.2.0 5.3.0 5.4.0 5.4.7 Warlords of Draenor 6.0.2 6.0.3 6.1.0 6.2.0 Legion 7.0.3 7.1.0 7.1.5 7.2.0 7.2.5 7.3.0 7.3.5 Battle for Azeroth 8.0.1
Sometimes you can make money by crafting items with ingredients supplied by other players who give you a tip to make the item. This is not necessarily a reliable source at low levels, but it can be a good supplemental income source at higher levels, particularly if you have good recipes. And if you can charge for the customer using your materials (as opposed to materials supplied by him/her), you can mark those up.
You will have to buy [Mark of Blackrock] or [Mark of Shadowmoon] at the Enchanter's Study with [Secrets of Draenor Enchanting]. These recipes cost 5 Secrets of Draenor Enchanting so you will have to wait 5 days until you can buy one of them. It's worth to wait because with other recipes you get 1 skill point / [Temporal Crystal], while with these you get 5 skill points / [Temporal Crystal].
“That’s the impetus behind everything, is to just make sure that players feel like things that they do in the game will have great consequences or great victories or whatever it’s going to be, right? Ultimately, our job is to create a world and environment and mechanics that support all that stuff. And however the players choose to make their choices is really up to them.”

The most simple thing is TradeSkillMaster. This AddOn shows you quite an amount of information in the items tooltip. In my opinion, DBRegionMarketAvg the best source. It tells me the price, an item was posted on all EU realms in the last 14 days. Why not DBMarket? DBMarket only shows you the items value from your server in the last 14 days. This value often gets manipulated. Some people start to post an item with a 500g value for 500.000 Gold on the auction house for several weaks. As a consequence, DBMarket is rising towards 500.000 Gold.  If you use DBMarket with 100% and post your item for 500.000 Gold, nobody will buy it.