12€ for a bar is not that strange.
I bought some of them, and some more expensive ones at 20 or 25€.
They look all as sturdy, and none exploded in my friends hands or mine either
As usual when buying online.
Look at the feedback, and the volume of sales of the seller.
How their shop look like, and how are the other sales feedback and volumes.
Scan the comments, reject the stupid ones.
If near 5* with a high volume, you can generally trust the seller.
For the frames, maybe this is more complicated.
If you buy from Peter many times referenced here, you get a great quality.
And if a problem occurs that is clearly a warranty issue, you get a replacement frame( tried ! ).
I bought a frame from Workswell, their communication is quite bad but the frame is good.
And recently as well from Tideace who look very serious too.
