I had them refurb my D8 and it was $200.
The D8 was built to last, according to paul (or was it tom?) and if you want to keep recording on DAT, the D8 will serve you better than the M1 or D100.
I have not used my D8 much since they serviced it, but it still works like a champ whenever i do, and I love it like a little brother that I would leave home when i go to the concert because he would just get in the way.
You can have him for $200 if you want him.
I just had Pro-Dig service 3 M1's which I could not stand to see sitting around collecting dust on the plastic bags they were housed in. Each one was $200 in service alone, so unless you need that 7-pin in that DAT provides, I think you would be better served buying a different recording option.
That said, you can have any of my recently-serviced M1's for $250.
;-)