Anyone have links or info on where I might still be able to locate one?
That has actually been asked and discussed recentlly. I think you are completlly out of luck unless you can find someone locally that has some old stock (someone mentioned that one of the microcenters had some in store). You could get a sony dru-810a or a plextor px740a (I think there are still plenty of them around). Both are rebadged 1640’s.