Custom Invoice Reconciliation Application

I am looking to have a custom application developed for my steel distribution business. The goal of the application is to track customer invoices, supplier invoices, freight invoices, profitability, and payment status in one centralized system. Core requirements: Customer Invoice Entry Create a new Company invoice record. Enter invoice number, customer name, invoice date, due date, and invoice amount. New invoices should automatically be marked as "Red" (incomplete). Status Workflow Red = Customer invoice entered, but vendor costs and/or freight costs have not been assigned. Green = Vendor and freight costs have been assigned, profitability can be calculated, but customer payment has not been received. White = Customer payment has been received and the order is fully reconciled. Cost Allocation Ability to assign one or multiple vendor invoices to a customer invoice. Ability to assign one or multiple freight invoices to a customer invoice. Calculate gross profit automatically. Document Storage Upload and store PDF copies of: Customer invoices Vendor invoices Freight invoices Purchase orders Mill certificates Other supporting documents Documents should remain attached to the related job/order. Dashboard List all Red invoices (missing costs). List all Green invoices (awaiting payment). List all White invoices (completed). Search by invoice number, customer, vendor, or date. Payment Tracking Ability to mark invoices as paid. Record payment date and amount. View outstanding receivables. Database All data should be stored in a database and backed up automatically. I would like the ability to export data to Excel. Future Enhancements (Optional) OCR reading of uploaded vendor invoices. Automatic extraction of invoice number, vendor name, and invoice amount from PDFs. Basic profit and loss reporting. GST/HST reporting. Please provide: Estimated development cost. Estimated timeline. Recommended technology platform. Ongoing maintenance costs (if any). Examples of similar applications you have built. Thank you and I look forward to hearing from you.