I've had a series of quality issues with wire from Stern-Leach
Rio Grande. I haven't called Hoover and Strong yet to see if therumor about them going to line-item pricing is true or not.
You might try Rio Grande. They list Argentium as well as sterling,fine silver, gold fill, all kts & colors of gold & platinum in theircatalog. It's listed in all shapes & sizes, casting grain, wire,sheet, & solders.
You also might try aaproducts.com.