Spoke Replacement

[cloberth]

Although I haven't started yet, the video tutorials for spokes and wheel-trueing look pretty informative. There is one sticking point for me - spoke length.
Since installed spokes are bent already, I'm guessing that when I remove one of the good ones to measure it, I must take into account the bend where the nipple enters the hub? How exact must the measurement be? To the millimeter? Will it be possible to buy a single spoke online, or should I get one from a local shop?
Thanks

[roscoe]

I recently replaced one. I took the damaged one to the local bike shop so that they could find the correct size. Since you'll need to remove tire, it would be easy enough to take a good one down there with you. It is important that it is correct size. Only cost me $1.

[Alex Ramon]

You can either take the spoke to your local shop, or measure one of the old ones. If you have it removed, straighten it out as much as possible and then measure from the center of the head to the end of the threads. If the spoke is slightly bent from being on the bike you could add a millimeter or two.
You can order spoke replacements here (usually in bulk if ordered online).