My 2014 left front Air shock is leaking fluid. Does that mean replacement? What are the costs of replacement or conversion to non Air shocks?

Thanks in advance for your advise

 

The right rear on my 600 failed last summer at 82,000 miles. It was leaking and making a bit of noise. The Lexus dealer charged $2014 including tax of which all except $200 was paid by warranty. You can find the part cheaper on-line.