A good quality timing chain and gear set is 3x the cost of one for a SBC, hard to find good quality aftermarket pistons (that are made properly), and the ones out there are 2x what you will pay for SBC pistons. When you get to stuff like rocker arm assemblies, they are not made new, so you have to get rebuilt ones, and they are upward of $300 for a set. The correct steel shim head gaskets are hard to find unless you get them from Carmen Faso, and they are more pricey than the composite style (that are much thicker) available at your local parts store. Cams and valve springs have to come from Carmen Faso or Rus Martin--they are both great to work with and have good quality parts, you just pay more because all this stuff is made in very low volume compared to other engines you may be used to dealing with. I just rebuilt the one for my 65 GS and I had around $3000 in it when I was done, machine work and all. I also paid more and had the rotating assembly balanced.
Another example--if you need a manual trans flywheel for a nailhead, they are available in billet steel for $400, whereas one for a Ford or Chevy is available in cast and for under $100.
Main bearings for a nailhead will scare you when you see the price--unique to nailheads, so over $200. Rod bearings are cheap since they are common with some other engines.
