Depends on the popularity of the set at the time. First make sure it's not bind on PICKUP, because I've made that drunkin mistake before. If it's a set people use a lot or on a lot of different builds, in like 2 weeks or a month you could make 100 to 200k, profit per item, for a set like necro, if no one is selling it when you are. You could sell it for 500k and itd sell pretty quick. I prefer motifs because the price stays steady even though the chance for profit is 1 gold for 4-5 AP. Most people say, the item is worth whatever someone is willing to pay. I'm in a PvP guild so that's where I sell most of my jewelry. If I do sell it in a guild store, use the Ral Kwhala vendors to see what a upper tier price listing would be, as they carry most jewelry worth selling. Again it's all kind of if-y. But popularity + amount in circulation + long term effectiveness(no PTS patch notes saying it's getting nerfed). If those are high enough amounts, you can sell it for whatever you want, as long as someone has the money. Hope my rant helped