The basic CPanel protection is not what you need. You need user level access through server-side scripting and databases. I'd seriously recommend looking into either a CMS (Content Management System) or an extension of their CRM (Customer Relationship Manager). Not sure if there is anything out there specifically built to your needs, but with that many customers I'm assuming 2 database tables minimum, 1 for the companies and 1 for the pricelists. This is assuming 1 user per company.
If you go the CMS route, with that big of a table if you are looking for pre-made solutions Drupal or Joomla may have extensions to fit your needs.
If you are going the CRM route you should be able to pull data from a Salesforce or InfusionSoft and give the end user the pricelist based information from that query without the need of installing/building user access on the website if this is the only use for it.
I am grateful for your prompt reply but maybe I did not make myself clear. The price list will be a 70 page pdf to view. We will be using a password generator which my reading is that this will provide quite adequate security -- I know it's not Fort Knox but I think we'd be happy with that level when also combined with a username account number. What will be a pain is finding a particular UNSORTED username from what could be 2000 names if we need to delete or retrieve as cPanel do not provide automatic sorting of new names -- they just go on in the order in which they are loaded. I have used CMS (Contribute) which I find less than helpful. Hope this clarifies the problem.
Your last post did clarify more but I would still go with my initial statement. You cannot organize data the way you are looking to with Cpanel alone. It's not meant to maintain that large of a userbase. That's what databases are for.
Here's the basics of what CPanel is doing via a GUI: http://httpd.apache.org/docs/2.0/programs/htpasswd.html
It's basically writing to a text file. It's meant to be good for a handful of users, but not the volume you are describing.
If it is the same price list for everyone, you can just get away with one database with simply usernames and passwords and if successful redirect them to another page with the PDF. David wrote a tutorial here:
That is part 2 of his setting of your first dynamic website tutorial, but that one specifically talks about the login and database table portion.