Crepe Hair is dyed wool, so if you're allergic to wool then you should stay away from it. It can be purchased in some craft stores (check the doll section, you'll sometimes find baggies of 8" braids of the stuff in one or two colors), costume/makeup shops, and online. Alcone has it for the cheapest at $5 per ounce/yard. Stage Supply also carries it, and the orange is a brighter orange than Alcone's. The Alcone orange is kind of a ginger, orangutan color. Ash Blonde and Dark Blonde are the same color, Strawberry Blonde is nice and golden, and Auburn is like a red-head in case you didn't know that already. Yellow is very bright yellow, and looks best when mixed with Strawberry Blonde. Yellow Blonde at Alcone is the same as Ben Nye's Strawberry Blonde. You'll need 5-8 ounces to make a wig, which can be expensive, but keep in mind that it's a fraction of what it'd cost to make the wig from yak hair.
(Craft store white I got at Michael's, Ben Nye orange from Stage Supply)
Crepe Hair comes by the ounce in a yard-long braid wound around two pieces of
twine (looks like hemp). To use it, you'll need to use a steam iron to
straighten it. It takes practice to get good at it. Here's how I do it:
Turn your iron on the wool setting and let it heat up; mine has a steam and a
spray button, which are quite helpful.
Pull on the end to unwind part of the braid. Cut the twine as you go so you can
expose more of it. Don't pull apart the kinky hair, or you'll end up with a
bunch of springy frizzy coils that are harder to iron flat.
Starting at the tip, press your hot iron to it and pull the braid taut. Iron
along the length, untwisting the braid and steaming and squirting it, gently
pulling it until it's flat.
I usually iron sections the length of my fore-arm and hand at a time, and I
discard the very end piece because it usually doesn't lose it's kink and the
fibers are cut in half.
Now the end is nice and flat.
Grab the end and pull off sections of fiber, gathering them in a bunch
side-by-side. Leave some straight wool on the braid so it's easy to start
ironing the next section.
Grab your handful of wool about a third of the length so you can brush out the
tiny short bits that you don't need.
Turn it around and do both sides so you're left with the longer fibers.
I separate out the extra-extra long bits from the medium-long bits. This is just
one section ironed, but a full yard will result in a good fist-full of
medium-long fibers 6-8" long, and a smaller pile of 9-10" long fibers.
