That's because they're professional-level products. Adobe does have a deep educational discount though. BTW, if you think Premiere's expensive ($700), check out Final Cut Pro ($1,000) or Avid ($1,700).
I am glad for educational discounts. It always left students in a quandry, from my perspective. If you're in school studying graphic arts but cannot afford what is considered the standard graphic arts program in the "real world", how can one be expected to have the skills neccessary to succeed.
I know all about the cost of those video programs. I tried sneaking Avid Xpress Mojo into the latest request I made for a new system at my office and my business manager just laughed at me.