ok, no laugh.
but just to comment that i got a MP3 player 512Mb creative one (2nd
hand-about 1 month old, its a MUVO V200) at this forum for only
$140.
so let's see 512mb = 140, therefore for about 100mb, a reasonable
price should be $30 really.
But you should tell people more of the "changeable" or expandable
memory space, since it uses a memory card and not a fixed flash
drive. hence now memory cards are quite cheap, the buyer can then
upgrade himself by buying a 256mb or 512mb card at only $60-$80.

i believe the selling point is actually the hardware, not the
memory space you have currently.
my 2 cents worth. 