I'm not saying I'm condoning using cat-3 in place of cat-5, just saying that you can hit cat-5 specs with cat-3 cable.
I've had to do it in a pinch, and I got lucky.
We did certify that they were up to cat-5 specs at my previous job, I forget which tester we had.
It was yellow, could test well past cat-5 specs.
Isn't the biggest difference between cat-3 and cat-5 the more strict rules on number of twists per foot to insure consistent lengths of all pairs?
So theoretically cat-3 can hit cat-5, just not guaranteed.
Anyways, it is all academic.
If you feel up to doing your cables, you are careful, and you buy good quality cable you should be able to create cables up to cat-5 specs.
I do agree that for often moved cables use store bought stranded cables.
If you are not a detail person, use store bought.
If you have doubts, use store bought.
But if you want to custom cable, it is not particularly hard to do.
mike