What really does "If you say so" in this context mean? Example of the context:

A - I'm saying that price of the laptop is less than $500

B - It is an expensive laptop

A- I am sure it is less than $500

B- Well, "If you say so"!

Is it rude? Most of the references I came across on the internet say it is pretty rude.

Thanks a lot!
It means 'OK, I accept your opinion although I still have some doubts. I don't want to argue anymore'.

It may or may not be rude, depending on the context, the relationship between the two people, the tone of voice, the facial expression, etc.

Thank you for the response Clive!