Ecommerce stores online

Hi, would like a quote on building a small business-Ecommerce Online store using Shopify, with an initial capacity of 20 products but the website created should be able to handle 100 products in future. Features to include, pricing cart, capture customer email via mailchimp, allow customization of monthly subscription on gift sets, generate return slips, sync with inventory systems like inventora / craftybase. Require total job price, time to complete, what info you need to from my end & when can one start. Pls contact me soon!