So, I was looking at kits of roll pins and springs that are insanely expensive and targeted at gunsmiths. $$600 $60 for a set of roll pins? Really?

I just went to a roll pin manufacturer and ordered 20 complete sets of 420 stainless steel AR roll pins for $50.. Even that is expensive since I am not buying in bulk.

For springs, Springco comes to mind, but even they are pricey.

Spring kits are much cheaper at about $100 or so, which is still kinda silly.

Back to the original question: What properties of a spring for an AR do I need to look for? What materials, coatings or other things make a spring ideal for this application? I am not focused on the trigger group, as that is AR specific.

Edit: I clean and inspect my guns regularly and consider roll pins a consumable, if that gives context. Springs, not so much. Still, I would like to have a few sets on hand without any price gouging.