I've seen them around online, the DIY niddy noddys made out of PVC for under $10 and I thought, "um, yeeeeeah." That is, until my fellow Ravelry pal Lafemme got a cool looking PVC niddy noddy in her swap package. It was complete with caps and rubber "O" rings and just looked so professionally made that I became intrigued and set out on a quest to make a couple of my own. There are dozens of pages online with instructions on how to create your own PVC niddy noddy, but I found this site to be the most practical and complete - there's even a couple of instructional .PDFs that you can print out and take to the store with you!
I purchased a 10 foot piece of 1/2 inch PVC for $3.19, 10 - 1/2 inch couplings (I wanted to have extra on hand) @ $0.24 each = $2.40 and 4 - T connectors @ $0.28 each = $1.12. Oh, and since my sucky Home Depot wouldn't cut the PVC (other than in half so I could put it in the car), I purchased a cheap little wonky hacksaw for $6.94. All for a grand total of $14.13 (including $0.48 tax).
The result? Three niddy noddys for less than $15 plus a wonky hacksaw in case I need to make some more :) I measured and made a 4yd, 2yd and 1yd piece. The center shafts can be interchanged so there's no need to actually make more than one niddy noddy. I made two complete units, but kept a couple pieces of extra tubing for interchanging.