Good program for rasterization?

I work for a small company with about 35 employees. The only use we have for Photoshop is for Batch Processing used to rasterize PDFs (

At $700 a license, this is a really expensive means for what seems to be a very simple task.

My boss has asked me to try to find a cheaper alternative solution to save the company money, if possible.

Anyone have any suggestions (with links so I can check it out before presenting it to him)?

Thank you!