Build an Prestashop Module

We are looking for someone who can build an module for PRestashop 1.6> The module is an "Upsale" module that should create Vouchers for customers depending on what they have in cart. For example. We want to create a rule that if a user buys 3 of same product they should get an automated Voucher in their cart. Let say for example a "Tomato". So if a user adds ONE tomato in the cart when he then visits the cart to either see it or checkout a message should be displayed in the cart (The message should be editable from the module and can contain HTML, preferably with prestashop TinyMC editor). So when user see this message he can then add 2 more tomatos and the module gives him an Voucher of either % or a set amount. and the message disapears. So the messages are condition controled from backoffice by the module. For example: Display message if this many from this category are in the cart. Or if this amount is reached display this message etc etc. This module we will together also publish on prestashop marketplace and share the profit from 50-50. We are a big Company that runs a webshop and sell products and we therefore require someone who is well familiar with Prestashop and its system. And we have more projects we want builded so this is a first step, after this if we are happy with your work we have more projects. We will give you all the design in Photoshop files with instructions of the modules structure and features. The module also has to be installable through regular module installation in Prestashop