A few years ago, I read an article on Steve Goode's blog on making sand mops -- http://scrollsawworkshop.blogspot.co...-on-cheap.html
So, I ordered some Gold Flex sanding rolls from Klingspor and tried it. It worked great. But did I save any money? A little bit. At Klingspor, a 2" wide roll cost $14.95 and the mandrel cost $9.95 = $24.80.
A pack of 48 pre-cut strips cost $29.95, with the mandrell = $39.80.
But you have to consider the cost of drilling and cutting the strips. You will be cutting cloth backed sandpaper, so blades do not last very long. I use the FD-HD blades which cost about 50 cents each. It takes 6 - 7 blades to cut the fingers in the strips - add $3.50. One of the pictures, below, shows what happens to blades after cutting 6 2" lines.
You need to drill a 1/2" hole through the strips. Don't try that unless you have a method for sharpening drill bits. I use a Drill Doctor, but not everyone has something like that.
By making your own, you will get 60 strips out of a roll of sand paper, vice the 48 that comes in a pack. So, you will have a bit larger mop than a precut one.
A well used mop will last two or three years (at least mine do). Now that I only have to buy the sanding roll and blades I get away with a cost of $18.50 per mop - plus the time it takes to make it. Compared to the $29.95 for pre-cut strips, I save money. But, I'm a retired hobbyist. A production shop whould have to reconsider time & materials.
Something to consider - save a little money by rolling your own.