If you have other spools of wire to hand anyway you can easily make a length of twisted pair wire if you have a vice and a hand drill (manual or electric).
The procedure is as follows:
Cut two identical lengths of the wires you plan to use about 50% or so longer than the length of twisted pair you will need.
Hold one end of each wire together and line them up before clamping them in the vice.
Pull the cables together gently at the other end and ensure that these line up and then insert these into the chuck of your drill.
Now turn the drill to twist the cables together ensuring you keep some tension on the wires so they don't form loops and get tangled.
Keep going until you have nicely formed twists evenly along the entire length of the pair.
The overall length will reduce as the twists form so keep an eye on this as you go.
This is easiest with an electric hand drill but doesn't take too much longer even with a manual hand drill.
What @rachaelp said. We don't actually keep spools of twisted wire lying around. We grab the gauge, quantity, and length we need for a project and stick the ends in a drill.
