Hello!
Choosing a computer that costs B. $1,900 instead of one that costs $1,800 means that you'll have less money available for other purchases.
$1,900 is more expensive than $1,800. If somebody buys a $1,900 computer instead of a $1,800 one, then they will have less money to spend on other things.
If they purchased the $1,800 one instead, they would have an extra $100 to spend on other things.
I hope this helps you! Have a lovely day!
- Mal