Good old magic shortbow with iron/steel arrows works fine for you too. The range bonus over what knives would give might make it a little more "efficient," especially if you're trying not to loose money. As far as a monster goes, you could try ogres like the above poster said, or lesser demons in karamja volcano (usually nice and quiet on p2p worlds). If you dont already have it, the accumulator would help, but its not essential. If you want to use knives, try killing chaos druids or fleshcrawlers. While they may have a pathetic amount of hits, you will most certainly profit from the herb drops, and flesh crawlers are aggressive meaning you can "afk" a bit if you have a decent defence level. For equipment, the best dragonhide set you can use, snakeskin boots (if you can get hold of them), archer helmet and an accumulator if you have done the quest/are prepared to spend time doing it.