Shopify app plugin

I'm looking for someone who can create Shopify app plugin. We need to calculate when a user has reached the volume level of a pallet for shipping and send that data over with the order. It would also need to show the end user when they have reached a pallet volume in cart. Ideally, we would want there to be messaging in the cart that states you have reached X% of a pallet for your order, only X% more to complete a pallet! Also, we want the volume to measure the full pallet to be editable. Would be ideal if we could give discounts as well to incentivize the user to order a full pallet. Ideally, the discount cost/percentage is editable. Please state your estimated time frame and your rate for this project. app is private - it will be installed only on one store