Pricing a basket

Write a program and associated unit tests that can price a basket of goods taking into account 
some special offers.

The goods that can be purchased, together with their normal prices are:
  Soup – 65p per tin
  Bread – 80p per loaf
  Milk – £1.30 per bottle
  Apples – £1.00 per bag

Current special offers:
  Apples have a 10% discount off their normal price this week
  Buy 2 tins of soup and get a loaf of bread for half price

The program should accept a list of items in the basket and output the subtotal, the special 
offer discounts and the final price.
Input should be via the command line in the form PriceBasket item1 item2 item3 …

For example:
PriceBasket Apple Milk Bread
Output should be to the console, for example:
Subtotal: £3.10
Apples 10% off: -10p
Total: £3.00

If no special offers are applicable the code should output:
Subtotal: £1.30
(No offers available)
Total price: £1.30

The code and design should meet these requirements, but be sufficiently flexible to allow 
future changes to the product list and/or discounts applied.
The code should be well structured, commented, have error handling and be tested.