I just bought my DK1 a Yamaha 362H flute. It was about $1700 on Amazon but I decided to check facebook marketplace before buying it. There were two options. One was unused for $1300 with receipt. They had bought it and then covid hit and their child had never used it.
The other was $750 but just been cleaned by the shop and looked nice in the photos. I decided if I'm going used I'm going all the way so I bought the $750. I have an appointment on Friday with a repair store to do another full tune up for $90. If it needs a total overhaul it will be $200, but that still is a good deal I think. I'm pretty happy for 5 minutes of work online and 30 minutes to drive and meet and pay the guy I saved $1000.
I usually buy stuff new/sale/used depending on how hard it is to find. But the most luck for me is usually facebook marketplace. Where do you look mostly?