Steam Marketplace Website

Hi YOU MUST HAVE STEAM EXPERIENCE I'm looking to build a replicate website for STEAM game Features needed: - Bots creation, setting up automatic send and receive of offers from Steam - Inventory page where prices can be set (Items of the same kind are stacked and price is set for all of them) - Add money \ cash out functionality - Home page with available items with search for items - Sellers will be charged a commission for selling their items - ID validation for deposits\cash outs Two websites that do it already: - [login to view URL] - [login to view URL] In your response provide the following details: 1. Do you have previous Steam experience? Show examples 2. Total price and how long would it take to develop? Thanks