I know it is more rewarding to use slayer but also seems to require a lot longer time which is time that may be employed on other money-making procedures. Also, if you would not mind, what would be the very best set-up (preferable below 20M) for OSRS gold the way you're suggesting. In the long run, is your training up to taste? You do not need the best things to train, the advantages are only couple of%, and also you don't need to train through Slayer, either.
The recommendation to train Slayer comes in high level players looking back and forth saying,"meh, want I coached Slayer, now I am 138 and have 10 levels to go...". The ability does offer two main benefits and that is: You always kill something distinct. You are able to cancel a job if you don't like killing something. The disadvantages is that eventually you get bored of it too, and you can just block 5 monsters. Also, some monsters aren't good for training melee. I would recommend training through Slayer, anyway, but you have read the facts, so up to you.
As for recommended gear, a Black Mask or even a Slayer helm is a absolute must. Beside that, you only require a whip (or a twisted weapon out of Dungeoneerin). The rest is up to you. For starters, I'd get Torag's plate and thighs, which supply the most effective protection-value ratio in the game (s'far as I understand ), black dragonhide for the magic-based assignments, and begin working on the Recipe for Disaster pursuit, which offers the most effective stat-boosting gloves at the game. I'd also get a ring of wealth (can't hurt), an amulet of cherry and glory boots - the latter if you have spare change, it's only a very small Strength bonus. In general, the whole thing ought to Buy RS gold cost you 2.5-3m.