What are those little cup-looking plunger things in the caliper called? And does anyone know if I can get the seperately, or do I have to buy the whole caliper?

Long story short, I was replacing the brake pads, and had the pin that holds the tension get stuck. When I asked my genius friend to get it out while I adjusted the lighting, he grabbed the plunger with the vice and bent it so it isn't quite round, and now I get a little brake fluid out from there.

So, I'd rather replace the plungers instead of the whole deal...any ideas?

p.s. I've already checked the local junkyards with no luck yet.