The Cardas Copper Litz with teflon insulation is between $1-3 per foot at Handmade Electronics, depending on the gauge. It is a bit harder to work with as the insulation must be stripped from the ends on all strands - I have found that a stainless steel wire brush on a Dremel works very well.
For silver wire I've been using DH Labs Revelation teflon coated wire, which is more expensve at ~$9 per foot at PCX.
For silver wire I've been using DH Labs Revelation teflon coated wire, which is more expensve at ~$9 per foot at PCX.