For transfers, if you only have a MD with analog out, then get an iMic, it's $35 and I haven't found a better solution, the sound quality is better than most soundcards.
Cheap mics--check out minidisco.com, soundprofessionals.com, reactive sounds, microphone madness. You can find mics that aren't too bad for about $50 (but you get what you pay for). You'll need to add a battery box in to something like that, though, for an extra $40 or so.