My warm white $1.00 direct from China panel LEDs are still going strong. There are some differences with the more expensive LEDs other than just mark up. Some add voltage regulation (usually listed with an operating range such as 10 - 30 volts rather than 12V). Of course, that can be a problem - many of the voltage regulation designs create RFI, which can produce a buzz in radios & even blank out weak TV stations.
Another add on is a bridge rectifier so polarity isn't required.
The biggest problem I've had with direct from China LEDs is getting more of the same lamp on a later order. Since most of the sellers purchase a batch & sell them until gone, the new batch may (and usually is) different. If you want all the LEDs to match, you better buy all of them (and a few spares) on the same order.
