For the mic, it depends if you need a stereo or mono recording. For mono, I could propose you something like an ATM10A/Audiotechnica
I use it for voices or ambiante music. The main advantages are the price and the possibility to put a battery (you do not need a phantom power)
For stereo mic, consider the excelent NT4/Rode
(you also have the possibility to supply it by a battery)
For a DAT recorder, if you need a portable device, take a look at the Tascam DAP1
. It's a proffessional solution, so it's a bit expensive, but you will find all you need: good battery, excelent sound quality, XLR conectors etc... Anyway, you will only find proffesionnal DAT, it's a proffesionnal format ;-)
For MD, I don't know the market. You have a lot of things, but you will mostly find cheap devices.
ps: I give you link to zzounds because you will find accurate descriptions, and they propose a really good servic in US.