100 pages is not "high volume". True high volume scanners are designed for 1000 or more a day.
You'll be fine with any scanner above "entry level". Even my $299 Epson Artisan 810 can easily do 20 pages in 6 batches, plus it has ethernet. It can scan to PDF on the machine (memory card) or to PDF on the desktop, and yes - each scan session can be a new PDF file.