I like your task because it's interesting. First of all, let me know what procedure you use to login to your corporate website. Is there a captcha involved in any of the steps? If your login is without any complicated captcha, then the whole monitoring task can be automated using a php script which can be initiated as a cron job. You need a server to host the script which can run at specific intervals automatically and check whether stocks are available. As soon as the script detects stock availability, it can notify you via e-mail or phone message. You can either place the order manually or if you want, even this step can be automated depending on the procedure for stock purchase.
This is just a brief and we can discuss the various options after I get a clearer picture.
Thanks and Regards
LXQ-CAD