We have used Pixis software for a few different custom tools. They are great and very responsive and talented. pixissoftware.com

So they can help us with Sage 100?

Yes, I would not have replied otherwise. 

Wright Office Solutions has many solutions already and may be able to help.  www.wrightoffice.com

Make sure whoever you use is a Sage Certified Developer so that they know how our tables relate or you can end up with a mess.

Depending on what you are looking to do there the Data Integration Suite may do what you want:   www.eidynamics.com/.../Sage100DataIntegrationSuite