Right. Although kinda depends on song/era. George's Gretsches were not cheap. Nor were the later Rics (12 strings, Macca's bass). The Gibson J160 acoustics were not cheap. In 65 they got Strats, in 67 they got Martin D28s (Blackbird, Julia) then George's gorgeous Gibson J200 (heard prominently on the intro of For You Blue then given to Dylan who's holding it on the cover of Nashville Skyline). Then of course the famous Kubicki built rosewood Tele. (And others, lefty and righty Jazz Basses, George's ES-335, for example.)
But yes, the Epi Casinos were cheap and used A LOT. Both John and Paul in both word and deed christened them their favorite electrics (cue Band on the Run). Paul's two Hofners were cheap of course. And of particular note, the most covered song in music history, Yesterday, was played on an Epiphone Texan (upside down, and tuned down a whole step.) So yes some VERY notable music on cheapies.