Shopify Buyback System for Customer Device Sales with DHL Integration

I need a Shopify-integrated system that allows customers to sell their devices to me through my website. Customers should be able to select their device model, answer specific condition questions, and get an instant price estimate... (Budget: €250 - €750 EUR, Jobs: API Integration, Email Marketing, PHP, Shopify, Shopify Development, Shopify Templates, User Interface / IA, Website Design)