Why is the Photoshop CS $700, while Photoshop elements is only $99?
How similar is photoshop elements to the full version of photoshop? Could photomanipulation(like the ones on this site)be done with photoshop elments?

yes, the average user can use elements and the results would be quite good. i have used both and elements has some tools you won't find in full photoshop and vice versa. you cannot use advanced masking techniques, layering, etc, however it has other commands that are available to be able to do it. for example, in photoshop an advanced user can use channels, adjustments layers, etc to color correct images and this person would know what they are doing and why. elements would be useful for someone who wants to color correct an image but does not know the theory behind doing it or how the program does it, they just want to do it. just click the button. if all you are going to do is photomanips, get elements or if you are worried about the money, try GIMP it is free and can do similar stuff.

BMC is right. I was going to help explain but my head hurts and I don't have the time... so... here, read this.
http://graphicssoft.about.com/cs/photoshop/f/elementscompare.htm

I can not use Elements mainly because I am a Photoshop guy, but if you are just starting out, Elements will be perfect for you.

Is Gimp a good graphics program? How similar is it to Photoshop?

Both Photoshop and Paint Shop Pro (does all the same stuff, but is cheaper) have free trial periods (or they used to). Photoshop Elements might have a trial period as well.

Go try them out for yourself, trying to explain them in words is a futile exercise.

Quote:

Words Make Hulk Angry!