Not at all. I'd rather say I'm a strong believer in the technology. The 30Ah in such a small F-F was definitely an "exaggeration", but 15Ah would be realistic for $15 physically and economically. The same for the T-F card earlier, its manufacture cost is only cents, the rest of the retail price is greed.

I'm buying great electronics off eBay with great success weekly. E.g. just got 2 SoC boards for $3.80 shipped, while they are $7 each everywhere. Or last week I've received 10 fully functional relays for $6, while they are $5 each everywhere. I had no problems buying components for my 3D printer 2-10 fold in price. But I would definitely note that the percentage of scum and counterfeit products from China merchants is growing for the past years, so always watch for the seller's reputation and return/refund conditions carefully while placing an order.