Keep farming... It's frustrating but you have to put in the time before you get gold... At one point I was sooo frustrated I deleted the arcane legends from my device to clear up space because I had officially given up... Then one day, all of a suddenly started getting gold, by farming and reached 1 mil gold.... Then kept farming and very little merching in-between and eventually had a couple mil and bought mythic wpn... Then from there started having gold that I was buying 100k+ vanity helmets and armor that I used to call players crazy and stupid for buying... Just gotta keep farming... Learn where to farm and how to farm there... Keep lepre, if you sell it you will regret it because farming without it is impossible... Farming with it sometimes seem impossible, which is why you usually need some sorta additional luck with it (best combo is lepre + Klass 25% loot reroll)...

Oh... Don't waste your money getting the grimm pet if you only have 300k or 400k, buy him when you have good gear, weapon, and like a good amount of gold to just spend... you'd be better off getting a pet like blinky if you were to spend 300-400k on a pet.... don't worry about buying pets yet, wait until events and do what you have to do to reach the tier levels to receive whatever pet is being offered as a reward.....