Recently, I discovered the Chinese version of Craigslist. A used Seka Exceed RDC frame costs around $600, and I also came across a complete bicycle with UT 8170 on Magene DB508 wheels for about $3,500. A non-SW version Tarmac SL8 is around $3,400, or a complete bike with SRAM Rival AXS for about $5,000 with a mileage of 100-300 km.
I think I will go this way when I want to build a road bike, or there will be a suitable option from the used ones.
Sometimes, you can find absolutely incredibly terrible builds from the trash. Tarmac SL8 S-Works with old DA Di2 10s, no front derailleur, and the left lever is SRAM Red, while the wheels are Lun (but I didn't understand if they just sell Winspace wheels or manufacture them), I do not know if the frame was a fake, but in the photos it did not look like one and the price was 2800.