Hi, I have read your description understand that you need to integrate sage 50(peachtree) with magento. I have experienced with designing and developing website in magneto over 8 years with customization of core, adding custom functionality, development of custom plugins, API-integration and adding payment method.
I would love to speak with you further about taking this project on. If you'd like to view my previous work, take a look at my Freelancer Portfolio
Thanks!