A not free option that I started using last year is Robo-FTP. You can run it as a service and schedule it. It has PGP baked in.

I use it to poll an FTP server every 10 minutes, download all PGP files found, decrypt them, then delete them from the remote server. The program and scripting language feel old school, but it all works.

Feel free to call and ask questions before you decide.

Good luck with your project.