Drupal 7 - Custom module for computing the cost of a product

We have a simple Drupal 7 portal with a few custom modules. The portal is used to store the company’s products, manufacturing instructions and customer orders. The portal is not publicly accessible and no VPN will be provided. The company is an instrumentation company specializing in geotechnical applications. This new mechanism has 3 parts: Quote, Pricebook and Product Cost. We are looking for a talented individual interested in implementing the *Product Cost* element of the project. Overall, we need to add a quoting mechanism to the portal. A quote is used to create other types of content (Order and Manufacturing instructions). To be able to quote a customer, we need to compute the cost of manufacturing a product and the margin required by Sales. This can be challenging and interesting because the Product Cost is a custom content type containing a collection of two user-configurable formulas using variables that need to be evaluated and them computed using the end-user formulas. The variables names and their potential values are already known and available on the portal but the formula needs to be configurable by the end user. The complexity of the formula may be similar to what someone would write in an excel spreadsheet, simple if-then-else with a few mathematical operations. To ease the implementation, the formulas are PHP based so they can be eval’ed within PHP. The functional specification and the design document contains all three elements of the module but the bid on this projection is ONLY for the Product Cost component The project will be handed off through github with the database dump readily available for the developer to start. The result will be giving back using github. Do not expect to be able to log to the portal to change the administration configuration, if administrative changes are required then you need to provide clear instructions to recreate any administrative steps. We encourage and recommend using hook_updates for database alters and other configuration updates. More documents will be available once the candidate is selected.