He has bought two laptops and sent one of it for change of battery and upgrading at this shop previously.
He was quoted $180 for the service, which he couldn't recall if it's more expensive or the same when he changed battery two years back.
He found out that the cost of a battery is $100 from conversation with one of the staff.
That means he could probably be paying $80 for the service alone.
He negotiated for a lower price by agreeing to change the batteries for two of his laptops.
In total, he paid $240.
If what the staff said is correct, he is paying $20 service charge to change the battery for each laptop, which seemed to be a good deal.
He watched while the staff was changing the batteries. The staff unscrewed a few screws, unplugged the connector, took out the battery and slot in a new one then plugged back the connector.
Suddenly, he realized that he could do it himself.
Why didn't he google to find out about it so that he could just purchase the batteries and replace them himself.
Now $20 seemed too expensive for a simple task like this.
After that, he googled for more information and decided to buy everything online and fix it himself in future.