to give you an idea of how much Gold you need:
2 Hero Mythstones to 1 Mentor is 500 Gold.
1 Mentor to 1 Hero is 1000 Gold.
2 Time Mythstones to 1 Master is 550,000 Gold
1 Master to 1 Time is 850,000 Gold.
Gold Find improves Gold drops
Item Drop improves Gold drops
Fortunate Perk improves Gold drops
Hound Pet can find buried Gold drops
Dealer Perk - sell Items for 10x Gold
Luck - chance for Items to be found with higher Tier up to Legend
Higher Tier Items sell for more Gold than lower Tier Items
Higher level Items sell for more Gold than lower level Items