Bryce Phelps made himself a beautiful oak spiral staircase and saved a ton of money by cutting up cheap IKEA oak countertops for the treads:
I went with a 4" steel pipe from the local steel yard buying 18'. Also purchased some angle and flat steel to frame out the stairs. My treads needed to be 22" long making the whole staircase 4' including the center pipe. The treads are 30 degrees, so you can fit 6 on one side or 180 degrees together. I had a total of 7 treads or runs and about a 9" rise. Take the overall height and divide by the runs = the rise needed. Once all this was welded back supports aren't needed and the stairs are very rigid.
For the treads I headed to Ikea and picked up the 8' NUMERÄR Countertop in Oak, traced and pattern and laid out the cuts in pencil with the grain all going the same direction. I cut the straight lines with the skilsaw and round cuts with the bandsaw. Took the router to the edges and followed up with some sanding and stain. Attached the treads with lags and wiped everything down.
It really turned out better than I thought and for a fraction of the price + you get to tell people you made it.
I write books. My latest is a YA science fiction novel called Homeland (it's the sequel to Little Brother). More books: Rapture of the Nerds (a novel, with Charlie Stross); With a Little Help (short stories); and The Great Big Beautiful Tomorrow (novella and nonfic). I speak all over the place and I tweet and tumble, too.