Just chiming in for a first response until somebody with real knowledge on Grecos shows up:
You're right, that's not a 1000. Alas all the pics are lacking resolution and the control cavity pic lacks the light to tell for sure but it looks like it is a little hollow between the cap and the body, if that's true that would make it an EG500C indeed. It also lacks the fret nibs so that would make it a 500 too, just like the 3-piece neck (just saw the 600 has 3-piece too).
As for the value - plastic parts, TRC and tuners were changed, no sticker (that's why you are here), so this lack of originality will certainly push the price down but maybe not that much for what's not a terribly collectible guitar in first place. Current prices can be found on the usual platforms and often depends on where you live and how much somebody wants one of those right now.
