Vintage Double Hose

Someone local to me is selling a compressor which she describes as a Bauer compressor, 3.5 cfm, triphase motor, from 1977 with newly changed filters and oil. My questions are:

1) any info on the specific model? I was told it was a "Dynamo" but couldn't get/find any more info on that.

2) what would a good price for it be?






Thanks.

It might be just a bad picture but it looks like a couple of pieces are missing out of the center hub on the fan.