I found this old, wooden tobacco pipe stand at the Heart of Ohio Antique Center and Flea Market in Springfield, OH. It was less than $20 and cradles the test tubes as though it were made for this purpose. I have seen similar wooden pipe holders and even test tube holders at Goodwill and on Ebay. You can also pick up a fairly inexpensive test tube holder on Amazon.
I lightly sprayed the pipe holder wood with a dark antique brass spray paint to update the look and add interest.
The test tubes are glass and came from Amazon. You can find them here. Though, if I were to do this project again, I'd use plastic test tubes with screw on caps to make them a little more durable and easier to use. Still, it looks nice and is usable the way it is now.
I'd definitely recommend making your own test tube spice rack as opposed to buying one of the pre-made sets which cost$30 - $150.
I love walking into my kitchen and seeing this spice rack. It makes me feel like a wizard uses my kitchen for alchemy and awesomeness.