Design Custom iPad based EPOS for electronics company

We are an electronics company looking for a custom EPOS (Electronic Point of Sale) software to be designed for our retails store across the UK. The application needs to be designed to UK accounting standards, including VAT & Second Hand VAT margin schemes etc. We need the system to be designed in such a manner that the following parts(modules) of the EPOS system can be added or removed as and when required by us: 1. EPOS system 2. Stock inventory ( Creating a database of all stock in the store including cost price, selling price and vat) 3. Purchasing (when we purchase a second hand item, we want to be able to record the sellers detail and description of the item being sold which should automatically be added to our inventory) 4. Branch module (this will allow the owners or area managers to view stock levels at any particular site/branch) Our requirements are that the EPOS be able to connect to the following hardware (wired/wireless): 1. Cash Drawer 2. Receipt Printer 3. Barcode Scanner We want the EPOS to run on the iPad and iPad Mini, and be able to run on the new iOS7. FINALLY we want to be able to license this EPOS to other people, so we require a licensing structure in place so we can issue activation keys for i.e. 12months. Will be beneficial if you already have a working EPOS system that you have designed in the past and can adapt to our requirements etc. Please DO NOT SEND us pre written messages, if you do so we will ignore your bid immediately. Please reply to us so we know you took the time to read our requirements etc.