The original shafts had a machined hard chrome overlay on them which is why the replacement shafts are at first glance expensive. There is some time, machine work and expense involved in producing them over and above what you might think.
I know, no one really wants to spend a couple of hundred on rocker arms. But the rocker system is really important to a good running motor. New rocker assemblies are near impossible to find now. Yes, you can maybe try to cobble, mix and match arms with new shafts, might work. But if you have a set of rockers that has done its job and is now in need of a little proper servicing, a real rebuild by someone who knows what they are doing is a pretty good option.
There is now only one USA based rebuilder left. Rocker Arms Unlimited in California. They have done a couple of sets for me. Not cheap I know, but correctly rebuilt the first time out. No crappy chinesium, bad machining, sloppy work.
Here is a general description of their process.
http://rockerarms.com/pages/rebuild.html
