Tariffs or not, I too find it hard to understand how I can buy an amplifier from China for £ 1.90 including free postage to the UK.
I wanted to buy two LM1875 chips but found I could buy two complete amplifier kits including PCB and components, delivered to my door, for half the price of just the chips from a UK supplier. Even if the LM1875 turns out to be a fake, and doesn't work very well, I can just buy new chips and have the PCBs etc. effectively for free.
Madness, but it's not the first time. I bought a DAC for £3.95 including postage, just to try it out. It's utter crap technically, but it didn't stop one manufacturer recommending it on their forum as a bargain.
S.