Bite the bullet, pay reasonable retail for exact right length spokes. If you haven't built wheels before, but Gerd Scraner's wheel book and read it through. Long nipples aren't a good way to fudge too short spokes; a spoke that goes through the inner rim surface and engages max nipple threads will hold tension the best and give you a stronger wheel. Also, double butted spokes are WELL worth the price, they'll hold tension best and give a slightly better ride. Small stuff-spokes, cables, etc., are a really cost ineffective place to save $. Using the right small stuff will give you results you'll ultimately be happier with.