I just bought one of those "1800lm" lights from Ebay and compared it to a known 500 lm lamp, and it has an identical beam. No where near the output of my Di Notte. I found what appears to be the same item for $17.90, advertized as 600 lm.
http://dx.com/p/lzz-t6-cree-xm-l-t6-...x-18650-197235