I'm glad I ran across this post. I have been looking at a 50 Watt LED for my 29 gallon tank and after seeing this I think that might be a bit extreme for that size of tank. The worst part is that two 10 Watts are almost as expensive as the single 50 Watt.
If you restrict your eBay search, you can find 10W LEDs for less than $5. I bought four of them for $20 (shipped).
Also, I was looking through some specs, and I think it might make more sense (for me at least) to get the BridgeLux. The test power on some of them are at 7W (which is where I want to run them) and the cost per LED is the same EXCEPT the spec/datasheet is available and you can drive some of them with currents to bring them reliably to a higher current.
Oh, and instead of buying from China and waiting 3-4 weeks, you can get them from an online electronics store within a week.