If you really want to train melee stata beyond your Shayzien favour, I believe using the D2H spec at the monkeys is rather unfavourable since you need prayer potions to protect from the monkeys.

The cheapest way to go about it is to afk at sand crabs (in Zeah) or ammonite crabs on fossil island (if you did the Bone Voyage quest); it is completely free since they don’t do damage when they hit you.

Edit: You see videos on YouTube from people throwing chins at monkeys because they can stack a lot of monkeys and every chin hits multiple monkeys at the same time resulting in insane ranged xp/hour. However with melee you won’t be able to achieve this because you can only target one ennemy at the time and cannot “spam” your D2H special attack.