Build a Website - 6 manufacturing websites under one domain

We are currently in the process of developing a new strategy for our range of brands / divisions, and require the re-design & development of our website(s). We are a multi-faceted manufacturing company with several quite different products and industry sectors. Following recent plans for business development of certain divisions & the identification that the existing website does not contribute to the direction we wish to pursue (one of clearly identified specialist divisions / companies under one umbrella group) we feel it is the right time to develop the site completely. We have also identified that the language, structure and CMS currently utilised is perhaps inhibiting growth and future development at the speed we would like, therefore would like to employ newer technologies which will future proof our website(s) for the foreseeable future. Objectives of the re-design: 1. Clearly illustrate to all website visitors that our different departments / divisions are specialist manufacturers of their products and not a small part of a larger diverse manufacturing company 2. Drive relevant visitors to each divisional website 3. Convert more website visitors - increase online enquiries, orders and company interactions 4. Improve Search engine optimisation for each divisional website 5. Reduce confusion experienced by website visitors regarding our product offering 6. Employ modern website language, technologies and CMS (open source?) so future development in-house and external is quick and efficient Following advice from a number of our agencies we plan to keep the entire site on one domain, however, I very much see the site being split into 6 distinct areas / websites within this with their own style, layout, framework etc which is appropriate for their market and the developments that are being enacted (such as new machinery etc and pushes into new markets). As such, we would consider the utilisation of 6 separate CMS to control each area (which I would hope would allow for easier development of that particular section in the future) but again happy to discuss whether this is sensible. The separation would be as follows (I have also attached a very basic schematic to indicate the separate divisions - marked in different colours): 1. Group website (top level domain with info on the company as a whole / group) 2. Printing & Engraving 3. Engineering 4. Bookbinding (e-commerce functionality required) 5. Labels Direct (e-commerce shop) 6. iTagged (not a traditional e-commerce site but does need the functionality to be able to place customised orders) We have an inhouse design team and a graduate developer, therefore would be a part of the design process and would be happy to build the page content, so I am not looking for a straight migration as we feel this would be very complicated and we are prepared to do part of the build (if this is feasible). To start with I am keen to get indicative prices for the proposed project (although fully appreciate it requires further discussion to finalise) along with ideas of CMS and language etc that would be employed.