OpenCart Plugin or Modification

I currently have an OpenCart website, and I will like to have the option to add a button to specific products to "Make Offer" (see picture 1) It can be either done by writing a plugin or modify the opencart files. Currenty working on a OpenCart Version 1.5.6.4 Job to perform: -Backup current website and restore it in another domain to testing -Create a plugin or modify to Opencart files to offer the option to accept offers that can be added under the product information, under Data (see picture 2) -The way to activate the Offer button on the product will be with a check box -A field where Admin can set the amount of money we can take for that product(see picture 3), for example, product is listed for $35 and Admin can take $30 for the item. If the visitor offers $20 , Opencart will display a message saying "Offer Rejected". Offer price will be not visible for the visitor , only admin can see what is the offer price -Validate the offer option with the offer price. For example, if the offer option is enable, the system will require to enter a offer price and vice versa. -By clicking the "Make Offer" button, the system will take the visitor to another page where he have to fill out a form with Name, Company, Phone Number, Email, Offer Amount, and display a security code (Captcha code) , (See picture 4) -If the offer is too low , the system will alert the visitor the offer is too low (see picture 5) -If the offer is good, the system will display a success message (see picture 6) -Once the visitor submit the information, ADMIN will receive an email with the information -Visitor will also receive a confirmation email with a formal notice I might be missing something and I might need to add more options, please keep in mind if you accept the job, you understand we need to test the option until is completed and working to our needs. We had a bad experience in the past with freelancers requesting money to be released to start working and we en up receive a bad work. We will will create a milestone and release funds ONLY AFTER the job is completed. If you are the ones to request money in advance, please don't post your offer in this project.