Questions on using an auto broker to buy "newer" car (2017, 2018) @ auction

triagainmama

Hi. I'm in Phoenix, AZ, and interested in buying a 2017 Lexus RX 450h. I think I can get the best deal by buying via auction, through an auto broker. My previous auto broker/dealer only bought from Manheim, only bought lease trade-ins, still under warranty, and rated in top condition.

I have 3 questions:
1. Does anybody recommend or discourage buying a car this way, and if so why?
2. Is there an auto broker/dealer you recommend in the AZ area?
3. What type of fees are reasonable?

Thanks in advance!