I worked on my GX470 - added freon, swapped out a Relay . .did a bunch of crap to it. Spent probably $50 in freon over a couple months, etc. The cans said my pressure was correct, but I never a flushed.
I would drive this car to the airport when I was travelling a lot, and leave it at Lexus for an oil change as they were $18 if you brought your own oil and they would do a full service work up, etc.. They would also take me to the airport, pick me up, - - could get a service in for cheaper than parking at the airport . . . .
Anyhoo . .
I had to go, the AC wasn't great, so I asked them to look at it and give me a quote.
They did a flush/purge/whatever plus replaced the Relay ($50+) all for like $130. They told me the system was way over-pressure and it had other issued, needed to be cleaned, I can't remember . .
I wish I could still go to that place

Some of the bills I see from people owning Lexus around here from Johsnon Lexus make my head spin.