The solution to the first case would be to pay for the Amazon copy, then download the PDF to read on the devices of your choice.

Regional restrictions are ridiculous, though. The film industry has tried to enforce this for years, but it is much watered down now compared to when DVDs first launched (and the encryption swiftly broken). Restricting books by territory is really a form of censorship. If China tries to stop a western book being read, it's criticised. Yet it's not so different from an American publisher preventing people in other countries obtaining their texts legally.