Let say you wanna sell your sword. Go search, type in the level of your sword. Then click DPS. If its off the chart then throw it to in-game market. If it's in the first few pages then you will know how much to sell.

Because what ppl will do when they search for item?
They will click to sort the DPS and Armor stat in that level of item.
If you have very low DPS/Armor but good stat. People don't see it cause its too far.