Not to start an argument here but I'd like to share a different experience. A couple of years ago I "only" did the seals on my 103 engine - not the Guides, when I replaced the Valve Cover Seal which was bad.
There was no smoking at all, just oil consumption & blow-by. Changing the seals dramatically improved (reduced) oil consumption. That and cleaning the tiny breather hole in the Valve Cover . My 2 cents
Sorry but I don't know the answer to the Price question