I recently went to the shop and purchased 4 items.

Three of the items cost:

$1.50
$3.00
$4.00

There was quite a long queue, and as I was quite bored, I was playing with my pocket calculator whilst waiting.

Very curiously, the 4 prices added to the same number as I got when I multiplied the 4 prices together.

What was the price of the 4th item?