General Method Description

"Plain" battlestaves are used as a raw material by high level players to create elemental battlestaves. Because of the speed with which you can gain Crafting XP doing this, and the difficulty in getting the battlestaves, they are quite valuable.

It used to be possible to buy a limited number of these from the staff shop in Varrock, but bots would world hop cleaning out the supply. When Jagex changed how shops work in 2007, they allowed players to buy a limited number of battlestaves from Zaff each day, the amount of which depends on how much you have done of the Varrock Achievement Diary: you can buy 8 per day if you've done none of it, 16 per day if you do the Easy tasks, 32 for Medium and 64 if you do the entire diary. Because of the limited supply these always sell for more on the GE than they cost to buy, making this an easy and fast moneymaker.

It used to be necessary to run the battlestaves to the bank (when you were able to buy more than an inventory's worth), but Jagex made a change in 2009 that causes Zaff to sell them to you noted. This means you can now easily get to Varrock, buy the staves and sell them on the Grand Exchange in less than a minute!

Note that I recommend listing battlestaves for sale at a couple of coins below the average price, not at the minimum price; it may take a couple of hours, but they will sell.