So we're down to 'significant cost' of upgrading an older bike basically. So let me put this on the table for thought. Tires, tubes, cables, bar-tape and brake pads are expendables. Eventually they have to be replaced. Same for cassettes, drive chains, bottom brackets and chainrings. The component cost and installation costs are identical regardless of the age of the frame they're going on. 'Aero' components are only an advantage over 40km/h and usually weigh more. Their main application (outside styling) is in TT events and solo riders on closed tracks. Todays high end bicycle frames are slightly lighter than high end frames 20 years back, but not necessarily stiffer or stronger. Cheap frames on the other hand still are and always have been a compromise.

So that 1988 Miyata with an Ultegra 10 speed cassette, Ultegra 6600 wheel-set, 10 speed DuraAce DT shifters, DuraAce chain, Continental GP 4000 700x 25c tires, Original Shimano 600 single pole brakes with updated Ultegra pads, Shimano bar tape and Avocet O2 kevlar saddle with titanium rails is more retro in style than in reality. Equipment and performance is very similar to that Specialized Roubaix Ultegra it hangs beside. Stick a couple water bottles on the Roubaix and the weight difference dissappears anyway.