Consider, perhaps, that if others put up items for a lower sale price, that the item is maybe not worth the higher price?
Items are given their worth by what people are willing to buy 'and' sell them for. Even crafted items are built from pieces you can find, thus creating no cost. The 'time/effort' required to level crafter and gear them out is negligible as you generally make money leveling and you can gear up by crafting gear with items you find. Once again, no cost.
Just because the first handful of people put, say, the Vanya or new Cashmere robes up for over a million gil does not immediately grant the item that permanent worth. It is no more correct them someone selling it for 100k or less.
Either use the open 'Market Board' (not Auction House) to make whatever you can from it, or put forth the effort to actually 'play the market' by buying out stock on things and re-listing for higher. People corner the market all the time and make crazy tons of money doing so.
