php random price distribution with counter per day

There is going to be a competition code from following prices:

Page will refresh every 5 minutes or at a specific interval of time and it will pick any price either A, B or C to distribute for customers.

Type A - 400 total prices
Type B - 133 total prices
Type C - 100 total prices

Now, when the code runs, it will select randomly either from A, B or C and maximum prices will be as mentioned above.

How can I write this logic in CakePHP or PHP syntax.

Kindly suggest.