Compiere offers open source ERP in a supportive environment.
 

As an open source ERP, Compiere code is available for you to customize as your business grows and changes. Other proprietary ERP solutions may leave you locked into the same business processes and software long after your company has outgrown them, but Compiere ERP software was made to adapt along with you. It’s not only flexible, but easy to upgrade, so that your business always has the most up-to-date ERP software features.

ERP and CRM without compromises.
  This invaluable ERP and CRM application is easy to install and implement. In just a few hours, you will be able to send invoices hassle-free! With Compiere ERP and CRM software there are no functionality compromises or irreversible implementation decisions. Compiere ERP software is a cross platform Java J2EE solution that provides: fully integrated ERP and CRM solutions both front-office (POS, Web Store) and back-office functionality inventory management automated accounting professional services solution managed distribution networks streamlined order processing