I get so much Temu spam that I finally gave up and decided to check them up. I compared 3 random items that the spam in Instagram was about - exact same items were 3x - 10x cheaper on AliExpress than Temu (~0.50 on Ali, ~5.0 on Temu, ~10 on Amazon). I haven't looked further but my impression was that they just ship stuff from AliExpress with a X price multiplier?