Go ahead and try it. I think most people who do this probably just
borrow a student ID from a relative or neighbor kid. But then you
have to keep pretending to be the kid if you need support, etc. Also,
there is no upgrade path with the educational versions.
There are other paths to getting the software cheaper. It used to be
that you could buy CS2 cheap and upgrade to CS5 for a pretty decent
savings over the list price of CS5. They started to close that hole
recently, with CS6 now requiring an upgrade from CS5, and not earlier
versions.
Last year there was a pretty decent Black Friday deal on CS5. I think
it was under $300. Maybe that was only because CS6 was about to come
out. But I will be waiting for a deal before upgrading to CS6.