So I am taking a Web Design class and we use Photoshop and Dreamweaver, and I go to Adobe's website and it would cost well over $900 for Photoshop CS4 Full and $400 for Dreamweaver. That is insane! I doubt these are even worth half of that. I mean Windows 7 is $200 and it probably was double the effort to make. 

Why are they SO expensive?

Because they're business and company products.

In other words companies are willing to spend that much.

But they're also very good.

But GIMP is similar to Photoshop and it's free. I doubt Adobe needs that much money. 

This is why pirating exists.. 

Most schools, and businesses have these products. Some normal people also have these products.

900 bucks or 40 bucks people would still pirate...

BTW Gimp isn't as good as photoshop just like you mentioned. Why are Mercedes more expensive than Hondas? Quality.

If gimp has 40% of the features as photoshop it doesn't matter as it's free. The price doesn't justify the quality as their programs are bloated and slow, but sadly my school uses them.

If it was $40 I would say piracy of photoshop would halve. If it was $40 I would have no problem paying. 

There very good..but then again I didn't have to pay for it..

I think its so expensive because mostly big businesses need it, so its a good way to make money.

this is because adobe sells to corporations and to schools. They dont really sell to the everyday user. The people that pirate it are the everyday users. They do offer student discounts and stuff like that where it will cost you a lot less.

Adobe is a professional product.

BTW your school doesn't offer like a student version?

GIMP is also professional.

No, and student versions don't even have all of the features.