Thats all collectible/limited/special editions are today: marketing gimmicks. I remember not too long after Street Fighter IV and Resident Evil 5 came out, there was a member on this board telling people to buy the special verions of each(for $90) before they disappeared. Now those same limited versions can be found in Best Buy for the same price as the regular editions, sitting side by side.
If you like collecting special editions for the bonus content(like I do), then by all means buy them. But buying them for investment purposes only is pretty stupid. If you didn't know before, you know now because we are telling you exactly what 99% of them are: a marketing gimmick that isn't very collectible/limited/special after all. And considering these c/l/s editions cost $10-70 more than the regular versions(only to come down to equal or cheaper than the regular version in a few months) I'd definitely recommend against getting them when they are first released.