Our Brother came with software to scan to PDF for OSX. I can't remember the name of it, but if you install the Brother Control Panel (I think) there's an option. Then the computers with the software installed show up in the select menu when scanning using the "Scan to Image" option. Anything that gets scanned in shows up as a PDF in Preview.
I just did this the other night. No $150 software was required.
We have an MFC-295CN.