Kinda sad that my impulse is to keep it a secret for fear of it being nerfed....
Enchanted gold geode rings. Used to buy the geodes in the bazaar for about 10-20, gold bars 10 but the few I've seen lately are going for 100+. They trivial at 211 so maybe that's why they've escaped the bat so far. Luckily I bought every one I could find for a month back about 12 months ago, still have a bag or two full of em. Most gems that can't be bought from vendors have a recipe somewhere that trades for a decent amount, but have to check lucy to see, but in almost every case it has to be the magical version. Polished quartz rings went for 700 if memory serves, ditto for platinum amethyst. Think those three are all the LDoN gems. If you velium sitting around you can do quartz ones worth 1100.
Also if you have money to burn, you can buy architect BP's when you see them for 3k-4k, turn in for 10k