google "perforators" and you should find a link for them.
I had a handmade perforator that I gave away a long time ago.
I have seven blank pages of perforated "stamps -- If you'd like them, Olivares, send me your mailing address.
As far as googling "perforators" goes, be careful of new machines that do several tasks including perforating because many only "roulette" or slit cut/skip cut the paper without removing any material. True perforation requires the removal of material, most often a round hole although other shapes have been employed to separate stamps.
You can look for older/antique machines. Many are large and costly to acquire/restore, but there are table-top models that have been produced in the past.
Thirdly, you can use pre-perforated paper that you print/design to fit the spaces provided.
Lastly, you can produce your sheets of stamps and then send them to someone to perforate for you for cost or for a partial share by virtue of letting someone keep a portion of the works as "pay" before sending back the rest.
If you choose to purchase pre-perfed paper, I recommend William "Bill" Porter, who has many other goodies related to this site such as rubber stamps, gummed paper and the like => http://www.wcp-nm.com/
I have two perforators for line perfing as well as other older equipment that produces numbers and other symbols in perfed form.
Olathe Press sells pre-perforated sheets that you can either decorate by hand or use your printer:
Tangle Crafts talks about different ways to create the perforation:
You only need a sewing machine with no thread. This is the easiest way.