Have bought from this
ebay vendor before. You really can't beat the price of these things on ebay and *could* pay up to 10 times that at a local dealer. Also bought from another ebay vendor but can't find that vendor now. There's a lot of ebay vendors for the made in Ch*na ones.
My experience with the offshore ones is that if you buy a handful of them, you may find one that is faulty. I had one that had a flickering row in an array. For the cost, you can just toss it. Might be a good idea to buy an extra one or two.
I've also found that the color is inconsistent in the same order. I bought 4 warm white G4 type recently and half are more bluish than the other two. That really bugs me, but nobody else is going to notice. The light output was disappointingly low as well.
There are no industry standards like there are for 120 volt lamps. Trying to determine what lumen rating to get for ex. can be frustrating and you may find what you order is much dimmer than expected.
You can buy some very nice domestic LEDs but will obviously pay more.
Instead of just replacing lamps, depending on what you have and are trying to do, you might consider installing LED puck lights. I have found that I can replace a 1/2 size pancake/dome light with a puck light and not have visible screw holes. You may also find that you can install two puck lights side by side to replace a pancake light and not have screw holes showing. I bought 8 of these
ebay puck lights for $9.95 each. They are pretty good, have good light output and are lightweight.