First of all In this e-commerce website you should be able to modify or write a module open sources such as opencart or prestashop.
I am not going to write about all the details about e-commerce default feature such as adding products, categories etc.. Those are should be in my web site by default.
These are important list what i really want from you guys...
1- Customers shopping cart can not be more than $100. If he or she wants be buy couple things and if the total costs more than $100, there will be a notification "Your total price can not be more than $100"
2- Every customers have limit to buy for each product. This limit is two for each product. Customers can not buy more than 2 items for each products So you should put a limit for quantity. However if shopping cart is under $100, customers can buy another type of products.
For examples: * There are two MP3 players and total price is $50 ----> Works
* There are two MP3 Player $50 + 1 Iphone case $7 + 2 T-Shirts $30. Total price is $97 --- Works
* There are 1 Tablet PC $75 + 2 T-shirts $30 ----> Does NOT work! Total Price is $110 and Total price can not be more than $100
* There are 2 Tablet PC$75 ----> Does NOT work. Because total price can not be more than $100
*Lets say customers buy two t-shirts $30(Product ID 001) and 1 i phone case $7( PRODUCT ID 987) and his total shopping cart price is $37. After that he wanted to buy exactly same tshirt again (Product ID 001) ---> It does NOT work. Because customers can not buy same products more than two.
*Lets say customer buy two t-shirts (Product ID 001) $30and 1 i phone case(PRODUCT ID 987) $7 After that he wanted to buy a tshirt again $12 (Product ID 005) Total Price is $49 ---> It Works. Because He bought 3 tshirts but not a exactly same t-shirt.
3- Each costumers can have a limit to chechk out. Which is 2times / Week
*February 23 Customers Checked out $67 and Februrary 25 Customers checked out again $75--- > It Works
*Februrary 23 Customers Chedked out $67 and Februrary 25 Costumers checked out $75, Februrary 27 customers checked out $50 ----> Does Not Work because each customers can not check out more than two times in one week. And in his third checking out customers should get notification " You had purchased 2 times a week. Wait X(how many days left) days. Then you can use shop again."
*February 23 costumers checked out $67, february 25 costumers checked out $75 and March 7 customers checked out $30----> It Works
Thats all.... It might be looks complicated for some one because of my poor English however it is so simple. Please ask me if you have any questions about details.. By the way you do not need to design, after you choose your open source products such as opencart or prestashop then i will give you a theme to apply this project