gear farming is good if you can beat the other people who have spawn timers camped perma. I still get AoNs all the time, but I can't get to Terror for the non DT golem. I just take 2 alts and let them eat the dt while I kill it with the main. Also, tradeskills can still make you alot of plat. You just need to research and see what is in demand. DoN cultural gear is always in demand and as long as you can under cut the next guy by just a little bit, you'll get the sales. Twink gear always sells fast for me (mid end gear with no required lvl). People are always making new toons and looking for stuff to twink them. A few times a week, I just make rounds killing old world raid mobs and they sell out very fast.
You can also look up epic drops that are not no trade. Such as Cragbeast blood, Shimmering Aligned Ore, and tons more. Stuff like that always sells because alot of people do not have access to the zones they drop in and want to do their epics as fast as they can. There are tons of people who want to do tradeskills but are too lazy or too busy to farm. Those don't make you tons of plat fast, but it is a steady source of income off traders. I also have a mage that never leaves the bazaar. He sits in there day after day casting new pet gear when he sells out then goes back into trader and announces that he is now restocked. I never keep pet gear for more than a couple hours at a time. Small plat sales, but when you sell out every few hours every day of the week, it adds up fast.
For your big plat sales though, you need to farm gear or high end drops that are not no trade. Just research what named mobs are where and what they drop. Also, if you can kill them or not.