The phrase "10,000 lux" is making me twitch. Lights emit
lumens,
lux is
lumens per square meter. In other words, lumens is the measure of how bright a light is, and lux is the measure of how well a room is illuminated.
So what these devices are claiming is that if you use them as prescribed (sitting 18-24 inches away) you (specifically, your face) will be illuminated at 10,000 lux. If they're just illuminating a little 30 cm square, they could be doing it with as little as 900 lumens of light.
To achieve 10,000 lux, you need 10,000 lumens per meter of area you are trying to light. The easiest way to do this is probably to 4 foot long 40 watt fluorescent bulbs. You can buy 4-bulb fixtures, which will emit a combined 12,000 lumens and consume a total of 160 watts. Probably cost you about $50, bulbs and fixture. So for a to light a 10 square meter room, you need 10 4-bulb fixtures, 1600 watts, and $500.