Bulk buying in OSRS involves purchasing large quantities of items, like 26,434 partyhats and 4,161 H’ween masks, in one transaction outside the GE, saving the buyer the hassle of GE buy limits (e.g., 2 partyhats per 4 hours). With a single account (12 partyhats/day), it would take 26,434 ÷ 12 ≈...