Need pulg-in for opencart

General information for the website: product selling
Kind of development: Customization of existing website
Description of requirements/features: Opencart shows product group discount in the product page like following

iPhone
$101.00

10 or more $10.00
20 or more $20.00
30 or more $30.00

I am going to use HiMarket opencart theme (http://demo.opencartworks.com/#so_himarket_layout1 ) and will show product on home page based on user/buyer city.

I wanted to shows group discount on the front page for Deals of the day, Featured product, New arrivals and Best selling. Admin should be able to set number of products and discount amount - % wise or fix discount.

When user buy particular product, he has to pay fixed amount to enter into the group discount and when number of buyers count reach to group discount count, he will be eligible for discount and email will be sent to buyer to pay remaining amount.

Admin should also be notified.

Task to BE done.
for Each product on front page and description:
- Show number for number of minimum person required in group to get eligible for the product group discount.
- Show minimum amount to be paid to get group discount for that specific product.

Back-end (Purchased product.)
- Keep track of each product, number of buyer for product, payment.
- sent email to admin and buyer when eligible for group discount.

Other points that will come while discussion. You may need to modify other pages to work this plugin properly.
- few more things we need to modify in existing theme for this plugin that will be discussed in person.
Extra notes: