Economical replacement rocker arm set?

I'm not entirely sure the current set is what is causing the ticking. I was going to do the push rods at the same time but I guess it makes sense to do rods then arms.

I know that they wear down over time. I just don't know how old these ones are. I would assume they are older as they have some surface rust on the shaft.

Is there any way to double check where the ticking is coming from? Seems like the rods and arms is he first logicial place.
yes, the rocker arms can become worn, but maybe the tips could be re-dressed, if necessary.
If you are getting new pushrods, first make sure all of the valve stem tips are at the same height. Hopefully, when the heads were done the machinist was careful to grind the valves and seats consistently, so the stem tips end up at the same height, so you can get one length of pushrods which will fit all the valves correctly.