Chris Noel is the recessed switch magnet around these parts. if you do a db search of plug key, plug switch, plugged switch, recessed switch, you'll find his posts. Chris has sold a number of them for what i'd consider very reasonable prices.
i'm not sure i'd quite know how to accurately answer you value questions. i'd be most concerned about sourcing the matched switch, lock, key setup. i'd suggest diligent rigorous (daily or morning/night) ebay searches; quite a number of the 1970 models had those recessed switches and i'd think it's still possible to find a set at a somewhat reasonable price.
these days, i'm totally out of touch on tool kits' availability, prices. might be easier trying to piece one together. a number of the CB models for maybe a couple years before and a few more years after shared some of the same tools. there were some tools, as i recall, unique only to the 750... as i recall. i guess we don't have pictures in the website of an original tool kit..... ! used to be somewhat easy to get those kits 10 years ago....