Documents for E-commerce - how to manage?

Some background: Our company sells ingredients for further processing. As everyone who buys or sells ingredients knows folks who want tech data/spec sheets, allergen sheets, labels, SDS, certifications, etc.  We are looking for a way to have customers have access to common pre-sale/approval documents without having them all simply available for the entire world to see on an open fileshare website. This would be for smaller customers who don't buy in large volume to free up QA resources to attend to the more detailed document requests of larger and frequently more demanding customers.  We've looked into a few different portal sites but aren't sure any of them are our solution. How are any of you automating this task?  

A couple of potential approaches to consider:

1) What software are you using to manage your order processing, sales document generation etc? I've seen this be adapted to attach the spec, MSDS etc when generating a sales quote, and automatically email it to the customer with the quote.

2) A private section of your website hidden behind a login page. You're still sticking all the docs up on the internet, but at least you can control who has access to it - for best control customers would typically request registration manually from you when you first start trading with them. You could also just allow people to register themselves via your website, and this will dissuade some who might just be fishing for free information, but it is much harder to police access to it with this approach.