I need a freeware or cheap (less than 100 USD) tool that can give me
the rectangle in which a specified string is printed inside a pdf file
(containing just one
page). It must also be able to return the string inside a rectangle I specify.

The tool must be command line based or in some way integratable with Java. 

I also accept an answer where you give two tools, each with one of the
functions described above.

The tool can be under all open source licences that can be integrated
with a commercial tool (i.e. not GPL).

The tool must work under Windows.

An example of a tool that seems to have the features I need is jpedal
at http://jpedal.org/. It is just too expensive.

Thanks