Im a touch younger than some guys here (28) but I remember getting a soundwave , cyclonus and grimlock in the early 90s here in Perth. You think it was just old stock? I know the gold boxes were out then too.
Soundwave was in production from 1984-86 (and even continued to appear in all catalogues up til 86 too) - so it's not surprising that you'd still find him in the early 90s. A second production of toys like Cyclonus was done in 1988 or 89, so that would likely explain why you saw him there too. The Dinobots AFAIK were only released initially in 1985, so if you saw Grimlock in his original G1 packaging then that's more likely to be leftover old stock I think. Although the Grimlock, Sludge and Snarl were reissued in 1990/91 as part of the Classic reissues (gold box).
We touched on this last year. Paulbot had some scans of an old toyworld catalogue he put up:
http://otca.com.au/boards/showthread.php?t=15091&page=2
I think this run (89-91 ish) of Soundwave, Starscream, Cyclonus, Ramjet was a legitimate Chinese pruduced run that had slightly different boxes/instruction sets.
Cheers guys! Makes sense now