I think that a dq really needs a marketplace. I’ve had to sell or convert so many items that are good, just because I already have one or they dont fit my style of play. Thus having a marketplace would be very nice, because you can sell that 3rd cataclysm to someone who is making a proc build and really needs it instead of converting it.
This would also open a lot if opportunities, especially being able to buy and sell eternal items so you can get the one you want. It would (or should) also be possible to sell and buy mythstones and crystals as those are pretty much the essence of dq from that all items are made.
Concerning the limitations of the marketplace:
Please add a level requirement to use it (maybe 80 or 90¿?) so it doesnt ruin progression by being able to buy cheap legendaries at level 50 and you have time to learn the game before having access.
Please do NOT add a tax to the marketplace (like taking off 10% of your profit) as the marketplace is also an opportunity to make money (by buying and selling).
You would have to think about what type of marketplace you would want to create. A trade marketplace (i.e. "offering cataclysm need mythical chakram), or rather a system based on money (the latter seems better to me).
I would make the trade with crystals different from the trade with items though (like the runescape trading system for crystals), but I would not like an auction-like system for crystals as this would drop the prices (if the runescape trade system is too hard to implement this would be fine too though.)
Please add suggestions and I will edit this post if they seem better (or I like them XD)
Also excuse my spelling, writing on a phone is hard.
EDIT: for those of you who dont know the runescape trading system, it is a system that sets a price at the beginning bit takes into account the average price sellers want and the average price buyers want and stuff like offer and demand to create a “guide” price that allows less than a 2% margin for profit (generally). It essentially creates a guide price for an item but you can offer for less (it sells instantly but you only get ~guide price -2% or you sell for more with the risk of waiting long or not selling at all but you might be able to get ~guide price +2%). The prices are rather static so they dont react to price changes or offer/demand changes immediately (to prevent price manipulation). This system creates an environment with relatively stable prices. If you want to read more, here is the link: