Personally, I tend to stick to Reagents; post them for a little more than their standard sell value, wait a bit, then profit. I guess there’s some players out there who just want brewing EXP or something like that. Last night I put up some rare gems for 150 Galleons a piece, and all of them sold out.
I made 16,500 just from them; I am straight-up BALLIN’.
Siren Top/Viking/Thane/Atlantean vanity items, they sell for a good chunk of change due to not being trivial to obtain and unique. Viking can go for 5-10k depending on the item, Siren Tops sell for 20k, Atlantean can go for 10k-20k, Thane goes for 25k-30k.
Saint Lily’s, I grow them at my base while I’m working on building and then sell them after. Usually sell somewhere around 90 at a time and make about 20k.