My ERP vendor says they can offer a similar system and it will cost a lot for them to integrate with AspectPL.

No on both counts. ERP systems cannot and do not provide the MES functionality and real time visibility of AspectPL on the production floor. Furthermore, the AspectPT team works with your existing ERP vendor or in-house IT staff to complete the integration – often at a capped cost so as to avoid any risk exposure.