I do not understand this statement. The decompression of the files should only deal with the output of the Ultra Sound Echo. I believe you are still going to need that $500,000 machine to create the files that the $500 device will compress.
You are talking about two different things here:
1. Image acquisition devices (that as you say would cost ...say $500,000)
2. Image compression softwares (that will now cost $500)
Image compression softwares is important when you consider transfer, storage and retrival of high resolution images which are *large files* and plus the related medical data associated with the image.
I know it since worked in the field of Medical imaging (Dicom) :)