Amusingly, I thought this was a spambot for a second sinse topics that start with "best affordable" usually are ;D.
Personally, I've had various mikes I've used for different things.I used a fairly cheap but reliable (about 30 pounds or 50 usd), basic usb mike purely for skype purposes, because I didn't fancy a headset mike at all, as I can get far better sound from my good headphones or speakers.
while the stand mike was reasonable, I wouldn't use it for recording.
I then have a rather expensive standard voice mike used for singing type affairs, though i've not used that in windows.
Myself I always do recordings on the rowland r09 which has in built sterrio mikes. the pickup range isn't huge, but the quality and even spacial difference betwene the mikes is pretty good. Also being quite small it's easy to stick in places.
The only downer is trying to record gameplay reviews sinse I obviously can't use headphones and a digital recorder at the same time.
for general recording though, whether voice or something else I'd recommend the roland or something similar.
It's quick and easy to use, plugs directly into a usb, and converts instantly to mp3 or wav of various bitrates, and also sinse it's literally a turn on and point affair, you don't even have to muck about with complicated software.
there are probably more advanced software options involving recording programs and mucking about with sterrio mikes of some kind, but personally i've never been dissatisfied with the r09.
It's what I've done all my game reviews on (just by correctly positioning my computer speakers and setting the pickup volume on the mike), and also what I did all the tdv recordings of Brutus' voice on.
With our dreaming and singing, Ceaseless and sorrowless we! The glory about us clinging Of the glorious futures we see,
Our souls with high music ringing; O men! It must ever be
That we dwell in our dreaming and singing, A little apart from ye. (Arthur O'Shaughnessy 1873.)