my three suggestions

1. Add an option on a stash tab / sale tab to reduce prices by a set percentage or a set amount, like -1 divines or -10% discount.
2. Make a data analysis at the end of every league, and buff the least used notables on the passive tree, least used ascendancy nodes on ascendancies, least used active and support skill gems, and the least used unique items.
3. Either limit the amount of map-juicing options for maps, or improve the performance somehow so all content is doable without frying out GPU's or your servers.