As an Ironman my go to are Paladins, average 1.5M cash p/h and a bunch of Chaos runes which I save up to purchase Onyx's.
Wilderness Slayer is also useful for potions. Now a days I keep T6+ and insta-sell any tiers below and use the credits to purchase Anti-Venom+ (4) which I either use for Zulrah or drop trade and sell for GP's.
It's not hard to make money. If you want big change, hit up bosses (Zulrah/Godwars) and sit there. It's all RNG based, may take you longer than others to get loot but either way you're going to get loot if you stick around.