You need a PPC-based Mac. PageMaker 7.0 will run on MacOS 9 or under the Classic environment of MacOS X. It has MacOS X icons. PageMaker 6.5.2 dates back to System 7. I believe that it will work, but I am not sure.
You can get it from any place that sells Mac software. If you are a university student or the parent of a high school student, then you are eligible to make purchased from the Education Store at Apple's online Apple Store. You should be able to get it for $200.