Help with Olympus voice recorders?

I work for a doctor, and I've been instructed to find some information on these, but I cannot find any that really answer my question.

My doctor uses a Phillips Voice Recorder. The file types we get from these are .MP3.

We need to send some of our audio files to another business for their own transcription purposes, and they tell me that they use the Olympus Voice Recorder (they use the WS-500m I believe). They say that their voice recorder and programs are not compatible with what we have.

Now my question is: My doctor was thinking of buying the same one, but it is over $200. I've seen other Olympus Voice Recorders that go for much cheaper, as they are much more simple types (whereas the one he was looking at has an music player? Unnecessary for our needs). Do all the Olympus recorders create the same file types? If not, is there cheaper recorders that produce the same file type as the one this company uses?

Basically, I'm looking for the cheapest alternative to create the same file types and be compatible with their programs, as they refuse to try out our programs (which are free, might I add, so this is annoying me).