I just checked the McMaster Carr site. I didn't make a comprehensive search because I didn't quite know what to look for.

I googled for wire fishing leader. I found some .011 dia wire leader at bass pro, 20lb test, 200 ft for 5$. Another site had 30' spools, .008, 10 lbs, under $3 at farm and fleet. As near as I can tell, these are stranded.

edit: I found some leader at .041 d. Getting closer. I'm sure you can do your own search. Some leaders are plastic coated which would help with the abrasion issue.