Multi-marketplace price & stock sync panel (WooCommerce, Trendyol, Etsy + more)

Multi-marketplace price & stock management panel I'm looking for a developer to build a web-based panel that manages my product prices and stock from one place and syncs them automatically across multiple sales channels. The system will run on my own server. Technology choice is up to you — please tell me what you'd use and why. The core problem My product prices are tied to a daily-changing cost value, so they change constantly. I currently have 1000+ products and updating them one by one is a nightmare. What I want: I enter that daily value in one place, and all product prices are recalculated automatically and pushed to every connected channel. Pricing logic Base formula: per-product labor value × 2 × daily value The labor value must be definable per product. The daily value is entered from one central panel and applies to all products instantly when changed. Flexibility is essential: I must be able to define different pricing formulas for certain product groups. The system should not be locked to a single formula, and new formula logic should be addable later. Sales channels (integrations) Price and stock sync across: My website (WooCommerce / WordPress) Trendyol Hepsiburada Pazarama Etsy I want to be able to add more marketplaces in the future, so the system must be built to allow new channels easily. Note: Etsy uses foreign-currency pricing, so prices calculated in local currency need a conversion/margin layer for Etsy. Discount logic The base price applies to all channels. On my website (WooCommerce) I need to apply a discounted price (at a rate I set); other channels receive the undiscounted base price. Stock Stock sync must be two-way: when a sale happens on any channel, stock updates automatically across all others. I need to map each product to its marketplace codes/barcodes from within the panel (my stock code is not the same as the marketplace barcode). Panel features Product list showing image, product name, stock code, stock quantity and price. Bulk and single price/stock updates. Per-product marketplace code/barcode mapping fields. Preferably a PWA (installable on phone), able to run on a subdomain. Users Single user (me) to start, but I need to be able to add more users later. Timeline I'd like this completed in around 1 month. Since the scope is broad, phased delivery is preferred (website + Trendyol working first, then the other channels). In your proposal, please include: Total price and payment plan Realistic delivery time and phase plan The technology you'd use and why Examples of similar work (marketplace integration / e-commerce) Post-delivery support/warranty terms Confirmation that the source code will be fully mine