Well, $50 for a 4GB drive is rather expensive. I've just checked a German electronics shop and they sell a similarly shaped IDE CF-card reader for 7 Eur / $10 and a 4GB CF card for 9 Eur / $13.
$50 vs. $23. I don't think this DOM is such a great discovery.
Not to mention that the cheapest 4GB DOM I could find in Germany is 60 Eur / $85. So the CF solution is probably a lot cheaper than $23 in the US, too.
