I've put something together that I think will work.

1. curl downloads this page that appears to search for the 3008WFP.
2. The page is greped for 3008WFP
3. wc counts how many instances show up. With no stock, 2 instances are returned.
4. If the bash script sees more then 2, it sends a notification off via GrowlNotify
5. If the machine is idle, Growl passes the notification off to Prowl for delivery to my iPhone.

Tossed the script into cron to run every 10 minutes.