It depends on what types of windows, frames, insulations you will choose. Also there are many windows brands with different prices. But I don't recommend to save money on this. You can find all necessary information here Window Replacement in Los Angeles and than make a decision.
The average national cost of window installation is $5,023, with most homeowners spending between $2,579 and $7,466. This data is based on actual project costs as reported by HomeAdvisor members. That's what I found, information is actual for 2018.