Echoing some of the previous sentiments, I would agree that slayer has transitioned from a luck based income method, to a more steady stream of income. Because Jagex has, for some reason, put almost all the focus of large scale money making on bossing, the gear released through bosses has devalued slayer drops past the point of return. However, normal drops from many of the higher levelled slayer monsters can add up very quickly. This, in conjunction with the incredibly low amount of resources required for players to use combat, makes slaying at a medium to high level quite profitable. Sure you might not be looking for that 3m whip drop that was once coveted, but if you keep tabs on what you bring in via Slayer you will realise you can gain more than you first believed.