Your neighbor was rude.
There are only 2 reasons to ask someone how much they paid for something, whether it is your beloved Yorkie or a new purse.
The first is reasonable. They love what you bought and are interested in purchasing the same thing.
The second reason is to judge you and then spread it around as gossip.
Try to judge the motive and answer accordingly.
You could go shopping and blow $1,000. for a bunch of stuff that fills your closet and garage and then ends up at the landfill in 15 years or spend the same thing on a puppy that hopefully lives 15 years and fills your heart with joy everyday!
Everyone has a choice on how they spend their time and money.