Why go to the bother of making your own paper? Mainly because it is cheaper and better than what one finds in a store.
I will be describing what is known as "backcoating" in the origami world. I didn't invent backcoating. There is a description of this in the book: "Decorating and Enhancing Paper for Origami". The famous origami master Yoshizawa is known for backcoating with methyl-cellulose.
The thing I figured out was that masking paper (backcoated with tissue paper) makes fabulous origami paper, and it is dirt cheap. Masking paper is sold in many sizes at almost all paint, hardware, and auto body stores. It is available in a wide range of widths. I generally prefer the 12", 15" and 18" rolls. It retails for about $6.00 per roll. As it is common, one can pick it up at a garage sale for even cheaper; last weekend I got a couple rolls for 25 cents each.
Methyl-cellulose is sold at wallpaper stores for around $4.00. A little goes a long way; one needs only about 1 tablespoon per quart of water to make paste.
I made the final process more efficient by using clear plastic squares as tracing and cutting guides.These were purchased at a plastics shop. I forget what they cost , but they were in the range of a few dollars or so, and they last forever.
Although not necessary, to reduce clean-up time, I lay the paper on a two-foot by four-foot, thin sheet of lexan plastic, rather than on a table. These can be obtained for next to nothing at a plastics store. Check the discount bin for sheets with scratches.