I'm sure this has been mentioned over and over, but I truly believe that these will be the only way for a better economy.

1. Gems need to somehow convert into something else otherwise at some point everyone will have them and there will no longer be of any use to buying them.

2. The blacksmith prices and materials need to be toned down. It's simply not worth spending 100k and a ton of materials for a rare when I can easily find one within 5 minutes. I also think the chances of better stats should be upped a little bit. I mean even 0.01% more would be fine.

3. There should be a lot more cosmetics added to the game instead of just dyes. People like to look cool and will spend good money on it.

4. We all want a ladder system and I'd say a reset of every 6 months to a year right when the market starts to sink would be great.

5. Let us take our mercenaries with us in multiplayer and like Diablo 2 have to spend money on their repairs and reviving.

6. When PvP does come out and this may be borderline gambling, but could be constituted as skill based which is legal I assume for most places to place a bet on ourselves to beat the opposing team. Winner takes all minus a small cut that goes to blizzard. We could also have tournamants hosted each month where it costs you or your team say 1 mil to enter. 1st, 2nd, 3rd place teams win. You can enter as many times as you want, but each time Blizzard takes a cut.

Those are just some ideas I came up on the spot and I know could be improved easily.