Need to build Agent AI for Quotation Creation

We are looking to build an Agent AI which : Takes the input of quotation request from Email, PDF, Images, Website Enquiry Extract the data of enquiry and check the erp system to match the right products for the requirement Prepare a quotation based on the customer requirement and available products Checks wheather the quotation is right or not Sends to sales team for approval and once approved sends to end customer ERP is already there and built with PHP. API's should be created from ERP to communicate with Agent. Agent should be able to understand products and map them with customer requirements through cementic approach. Agent should not invent. We need to know the cost and timeline if : Agent is built from scratch using LLM, LangGraph, Python etc and if created using already available AI (such as claud)