Build an Online Store (Build your own box)

We are an e-commerce company based in Bangkok (site: [login to view URL]). We deliver authentic Thai gifts to foreigners and expats across Thailand and internationally. We currently offer 4 curated boxes on our website (4 products only). It runs on Wordpress & Woocommerce. We would like to introduce a new feature "Build your own box" allowing customers to actually customized the content of the box. We would have about 40 products listed and would like to allow users to tick / drag & drop items to the box. It needs to be responsive since a significant share of our traffic come from mobile / tablet. What would be an estimate of the price? Below are our specs Front end: - website currently sit on top of Wordpress & Woocommerce (we'd like to keep those for now and not move platform if possible) - build your own box. Visitors first choose between 3 unique pricing categories: 5 items, 6 items, 7 items the pricing only differs depending on the number of items they want, not the type of item afterwards - total of 40 products (no pricing indicated, only picture + text + zoom-in feature for each pic) - user tick a box or drag product to add to the box - 3 categories of products to be displayed: touch, smell, taste (while shopping it should be easy for the visitor to switch from one category to another) - mobile / tablet friendly from day one (significant share of our traffic come from mobile) - Add box to cart (not each item in the box is added to cart, only the box once it has been finalized by the user) - 3 options once done with box personalization: build another box, order the same box twice, ship box now - payment: Omise (or COD) - international shipping options. Visitors decide whether they want it shipped within Thailand or internationally. - Shipping within Thailand is free. International shipping has a cost (we would provide the different pricing) - extra option (fast shipping / within 12h) at extra cost - total of 5 different pages (1 for the choice of box, 1 for each of the 3 categories, 1 for confirmation before being sent to checkout) - integration with existing checkout run on woocommerce Back-end: - we use Woocommerce as our backend. We'd like to keep using this one. It sends us e-mail notifications and integrates with Mailchimp for emailing lists - for each order following info need to be visible on email notification: name customer, e-mail, type of box, reference of each product for each box, delivery option, address, payment option (card or COD) - we would like to easily be able to add products to the selection of items later on (custom inputs: picture, text, category) if possible through Woocommerce.