This was an easy and cheap project. The total cost of supplies for two poles (including the beef jerky which is always necessary for these kinds of projects!) was $12.50. It took about half an hour to make two poles.
Step 1: Get to the store!
Before heading to the store, if your tent has built-in sockets where you insert the poles, see how snugly your old poles fit. If they're very tight, you'll need to find conduit that's very similar in size to the originals.
Second, take your broken poles to the store with you. Conduit is usually sold by the size of the hole down the middle, not the size of the outside of the pipe. If you have a 3/4" tent pole and buy 3/4" conduit to replace it, you'll be in for a nasty surprise later.
Once you've found the perfect piece, find a larger piece of conduit that can slip over it. You'll be using this as a sleeve to connect the pieces you'll be sawing apart in while.
Next is the hardware to hold the poles together. I used standard bolts, washers, and nuts to semi-permanently attach the sleeve to one end of each pole, and a clevis pin and hitch pin to quickly attach the other ends.