The problem really stems from the fact that the catalogue attempts to give a general indication of value for an issue, without accounting for more valuable signatures and other factors. In each case the price is for the cheapest signatures (page 299 again). Your hypothetical BC-48a radar came in at $45, less than catalogue for an ordinary note - but the commonest type is BC-48b, at $40, thus the radar is catalogued at $5 higher. The old method of premium pricing was abandoned a few editions ago because it was not well enough understood. Some "premium" references have persisted, which should be expunged shortly.