I also ordered a cheap battery from Hong Kong approx 2 weeks ago. It arrived just a couple days ago. So far I've been very happy with the performance. By the time I put my phone on the charger last night I still had ~35% battery life left in it. It was a typical day of use so I'm usually down to the low battery warning. (Energy Rom 6.5.5 BTW)
The battery I picked up was an Andida and is supposedly 2000mahs (vs. the standard 1500). From what I've read gauging the mahs a battery holds is tough an will vary based on the device and method used to measure it. So take the rating with a grain of salt basically.
Here's the ebay user who punts these things. It looks like there aren't any listed today.
http://myworld.ebay.com/obo_hk
For the best battery rating that that I've seen check out this thread over at XDA. This guy has done some serious leg work.
http://forum.xda-developers.com/showthread.php?t=583927