This tip comes from Maurie Taylor in Tasmania, Australia.

"I have a tip that may save some of you some money - always a good thing... I recently bought a little 2" velcro backed rubber mounted sanding disc for use finishing off bowls and the like. The retailers sell a limited range of sanding discs for AUD 4.50 per pack of ten. I thought there must be a better way - so I checked at the local tool shop and they sell 6" velcro backed sanding dics in a wide range of grits for $0.75 each. It is possible to cut 5 x 2" discs from one 6" disc. I obtained a short length of 2" waterpipe - good heavy wall thickness, and ground a cutting edge on one end to make a home made wad-punch. Stack your 6" sanding discs on an old piece of scrap (I've cut 4 at a time OK) and give it a good whack with a hammer and presto, a stack of 2" sanding discs. Using this method the cost of the discs is 15c each, and I've got a wider range of grits."