Green’s Dictionary of Slang

a notably harsh bargainer or grasping tradesman.

1607		Dekker & Webster Northward Hoe I i: You might ha tane mee ith streete, and not ith’ Tauerne entire, you Cannibals.
1630		J. Taylor ‘Fearefull Summer’ in Works (1869) I 62: The uncharitablenesse and ingratitude of those beastly, barbarous, cruel Country Cannibals.
c.1698		B.E. Dict. Canting Crew.
1725		New Canting Dict.
1867		R. Whiteing Mr Sprouts, His Opinions 21: ‘It’s five shillings to pay, sir.’ ‘Why, yer shabby cannibal,’ ses I.