Typically HV 22lr are plated and standard/subsonic are not. Just because its plated the cost isn't really a factor. Most cheap bulk packs are HV and plated except for CCI blazer while top shelf target ammo like Eley is lubed lead, standard velocity and pricey.
I've been told that the copper plating helps reduce barrel leading and acts as a lube, even though I've seen plated ammo with a wax coating. Personally, I think it's mostly cosmetic if doesn't act like I was told. I"ll let someone else verify.... Either way I don't lose any sleep worrying about it much.