Give it time, when the 3rd party API shuts down on 6/30 and mods can no longer moderate as needed, you might see some returners

Check if the weapon is meta, goto warframe market, price mine 1 plat cheaper than the cheapest if it has garbage rolls.

If good rolls are present i will price it mid range and drop it 50 plat weekly till it sells.

To me plat in hand is worth more than some potential higher price down the line.