Good lord, am I one of two people who can do optical MD transfers in this thread...
I picked up a Sony JE500 off of ebay a couple years ago for $50. I found that was the toughest part of the transfer; finding an MD player with an optical out. After that you can use your macbook optical in, a Sony D-50, a usbpre2 (bit perfect, I asked SD), all sorts of equipment to feed to a recorder.
So if you don't want to farm out your masters, you might look on ebay for a JE500, JE510 (as pjp has) or one of the other 500 series. Those are the cheapest ones if I remember correctly.
edit:
sent a PM to uncleyug & greenone about getting my MD unit into their hands as I'm not in a position to spend time doing transfers.