Spin Art Machines have been around for a while and I have seen them at craft shows for years.
You could buy a Spin Art machine for anywhere from $12 to $282 depending on the size and quality of the machine.
If you have a spare box fan and some card board, you can make your own at home for pennies on the dollar!
Step 1: Acquire Supplies
1. Box Fan - any size (16", 20", etc) : http://www.walmart.com/ip/Galaxy-20-Box-Fan-4733/10553592?findingMethod=rr
2. Corrugated Cardboard - I used the cardboard from a Husky air compressor cardboard box. Should be stiff
3. Chipboard - The size of the chipboard sheets depends on the size of the cardboard base cutout above. Use small chipboard sheets from Michaels or other craft store.
4. Push pins - Holds the chip board during spinning to the cardboard
5. Acrylic Paint
6. Mustard and / or Plastic Ketchup Bottles - Used to squirt paint onto spinning canvas (http://www.google.com/products/catalog?q=ketchup+bottles&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&tbm=shop&cid=2210169627730432471&sa=X&ei=DvW8T5D3HoOpgweSx-H3Dg&ved=0COcBEPMCMAA)
7. Drywall screws - for attaching cardboard base to fan
8. Phillips screwdriver or Drill with phillips drill bit
9. Large cardboard box - to catch overspray