I'm looking for sales figures in number of units or in dollars for the
Seiko SmartPad or for the Logitech IO, with numbers not older than 24
months.  I'll pay $20 for either number, $40 for both, and if you
can't find it exactly but can justify a good guess, I'll accept that. 
I don't care if it's 2002 actual, or 2003 projections -- there's some
wiggle room here.

Hello.

As of July 2003, Logitech had sold about 30,000 IOs.

Source:
From a Chief Executive magazine article about Logitech CEO Guerrino
DeLuca:

"When DeLuca looks at one of their newest designs, the Io Digital Pen,
he sees beauty in its simplicity, but also room for improvement. The
cigar-sized pen is meant for people with jobs that require lots of
note-taking. It uses an optical sensor to record handwriting as you
scribble on paper. After, you stick the pen in a cradle and download
whatever you’ve written to your computer. Logitech has sold about
30,000 of the $200 pens, mostly to early adopters who have to get
their hands on cool stuff first."
source: "Lord of the Mice", Chief Executive, July 2003
http://www.chiefexecutive.net/depts/technology/190.htm

This 30,000 figure represents about six months worth of IO sales
because Logitech began selling the IO in November 2002.
http://www.creativepro.com/story/news/18211.html

search strategy:
logitech "has sold" io

I hope this helps.

I'm not sure how scarce this information really is, so it may be that
this is actually a five star answer.  Anyway, nice job, and thanks.