Tradeinn generally had the best prices on the market in the past. But many of their prices are now aligned with the market (even bigger here and there).
I bought 5-6 times from them, and everything was ok, apart from a delay of 20-25 days on the last order in Jan 2024. They proposed me to wait or to request reimbursement, and I preferred to wait. Another issue is the poor technical description of the products: you must know very well the parts you want to buy, because you do not get detailed clarification on their website.
Overall, Tradeinn is not fraud. Maybe there was a problem with the carrier during delivery?