So I was servicing Pflueger supreme spinning reel and ended up overstretching and rendering practically useless the anti-reverse spring for the switch. Anyone where I can pick up a new one?

You can get it from Flooger directly: http://www.pfluegerfishing.com/Reel-Parts/reel-parts,default,pg.html

Perfect! Thanks for the link!

They may even comp it on a small part like that.

I did the same thing with a patriarch i used to have. they sent me the part free of charge. just e-mail them.