I just found these threads at the craft/sewing department:

1) Coats & Clark metallic decorative sewing thread (60% nylon & 40% polyester). It's fine in diameter, and is perfect for ribbing flies in size 14 or smaller. I found Gold (T34), but it must come in silver (they were out of it, I guess). Its a 200-yd spool for about $2.79. Its much more limp than metal wire and tinsel.

2) Coats & Clark transparent 100% nylon sewing thread, size .005 (T27). Should be good for scuds, shrimps, etc... Its more limp (and possibly stronger) than tippet material or spinning mono, and comes on a 300-yd spool for about the same price. Only problem is the large spool size (won't fit my bobbins)......