I understand that the word 'gaudy' meant bright originally but could the current meaning of 'gaudy' as in cheap and flashy be a relatively new definition coming from the architect Gaudi?

No:

[Middle English gaudi, gaud, prank, trick, possibly from Old French gaudie, merriment (from gaudir, to enjoy, make merry, from Latin gaudre, to rejoice) and from Latin gaudium, enjoyment, merry-making (from gaudre, to rejoice; see gu- in Indo-European roots).]