Add multi tenant - storefront option to existing Codeigniter app.

Hello,
for some time I am the holder of a script that works in a similar way to social commerce feature like fancy or wanelo.
It has features shoping cart. It can work in several ways, as affilite a script for wishlist users, or as a marketplace with paypal paymant gateway.
App Is written in codeigniter framework. Currently it is not installed because the project I began a few months ago, but due to other commitments it ceased to develop.
I would like to resume the project, so I'd like before it make available for users to add the possibility, which has recently been introduced for eg. https://fancy.com/merchant/,
or was previously available on:
http://storenvy.com.
Description of requirements/functionality: What to do:
- Take current app and modify so it can work as a SAAS app
- Create new instance for customer on sign up / payment
- Create new sub domain folder
- Create new DB
-Configure store admin panel
-Add 2-3 sample storefront themes which user is able to choose.(Bootstrap3)
-Configure superadmin/owner admin panel to give the capability of basic administration of storefront.(admin panel of script is done)
- Give basic editing css/html color/navigation and creating bacis pages eg. about us/contact for storefront owners.
CMS and Admin requirements: Namely - give users-seller the possibility to create an independent storefront, which would be located on a dynamically created subdomain like: user1 Which are a seller on the marketplace or / Which is new user want to simply open a storefront shop.
Like:
http: // myscript .com/user1 creating user1storename.myscript.com name of subdomain Which user have choose.
So now users can import their products from the primary marketplace, or add new ones that are automatically added in two places marketplace / user profiles + user storefront. And to add additional information (script gives only basic information, the holder of the store could extend them).

I would like the default storefront was added categories that apply to the marketplace.
After registering a new store, the user has to be taken to the administrative panel storefront, which is to be programmed with one of the topics:
http://themeforest.net/category/site-templates/admin-templates?ref=mootothemax2

The panel is to be able to change the basic information store, change the logo, change the subdomain on your domain adding products and control the sale.

Would be created or used ready-made solutions. For starters, I would like 2-3 theme from which a user could choose from. Necessary to the bootstrap framework.
I would also add the ability to easily edit the theme eg. Editing navigation, EDIT colors, theme, adding simple pages eg. about / contact - for storefront owner.
Specific technologies required: codeigniter
I'm open to suggestions, they can be used ready-made solutions (appreciate the cleverness).

Before the collaboration What I want to know the price? How much time do you need? Are you doing similar projects? What do you apply?

I'm looking for a competent, smart, honest and not expensive partner. I do not demand writing new code, I'm are strongly for the use of current solutions and configurations.

I do not have the space budget, but I can guarantee a certain amount of a regular monthly work. For the winning option is also a possibility later collaborate on development. Keep it amiss, offering price.
Regards
bart tomas
http://www.series99.com/web-development/building-saas-app-with-codeigniter-mvc/