Create a Shopify App - Ruby On Rails Developer - Shopify API

I want to create a very simple app for the Shopify network and would like to work with a freelancer who has created via the Shopify API previously. FUNCTION: The app will allow stores to set shipping rates on each individual item in their store, which are then added up to form the shipping rate at checkout. DETAILS: - oAuth for store only, not individual user authorization. - Import all or some products from store. - Set shipping rates per item. - Ability to set multiple rates (economy, standard, premium, etc - user configurable names) - When customer orders, they are offered choice of available rates (economy, standard, premium), each of which is simply a sum of the numbers input by the store admin. ADDITIONAL INFORMATION: - All scripting to be hosted on my own servers. Fine for you to work locally, but live product to be hosted with me. - Project will be for public use, although testing will be with my own Shopify store in the meantime. - Initial bid need only take us to a working product and submission to Shopify. I understand that they may require code revisions -- these can be handled/billed separately, as it is not entirely under your control. Please, it seems that lately everyone is massively overbidding projects. I WILL IGNORE YOU. Reasonable bids within the project parameters only. Thank you.