Scrape all PDF documents on dynamic website.

We are looking to get a quote to gather PDF documents from a dynamic website. We do not know how many PDF documents are in total. The site requires login and the site is ASP. We would like to use HTtrack however, we have been unable to configure it to download any PDF's. I would like someone to see if HTtrack is capable of doing this? If not, perhaps we would need a crawler written. Linux or Windows. Our budget is $100.00 per scraper paid by Paypal on Freelancer. We will pay upon confirmed test and operation of the scraper on your server.