I just pulled the trigger on 2 no-names off ebay for $6 each.
I went with these ones because they are 7.2V like the canon battery, all the other no-names are 7.4V.
B94 Battery For Canon EOS 550D Rebel T2i LP-E8 NEW on eBay.ca (item 120558056024 end time 17-May-10 08:55:59 EDT)

Good for you! I use mine daily.
I got mine in under a week.
Pretty amazing.

Four questions for those who have tried generic batteries:

1) Which one did you get (link)?

2) How long does it last?

3) Does it charge in the Canon charger without issue?

4) Does it display accurate remaining battery life on the camera?

Is there any chance of these batteries damaging the camera? or is the only concern that they empty out quick?

I've been using knockoffs for years on many, many cameras including the t2i. They work great and are almost as reliable as OEM, usually at around 1/8th the cost. That adds up over the years.

On the t2i, I seem to get a half-way indicator only, not quite as detailed in remaining life as the OEM. They do charge in the factory charger.

for cheap you can find the battery grip that allows you to use rechargeable AAA cell.
additionally it seems it removes the heat from the battery going directly in the body and limit the overheat symptoms

Battery comparison: original vs. knock-off
 

I did some comparison between a knock-off battery and the original:
http://ninofilm.net/blog/2010/04/08/...ginal-vs-fake/

Be very careful what you buy! I'm a bit disappointed. But I guess the 2000mAh thing is good.

To this date there is no such thing as a generic battery grip for the Rebel T2i / EOS 550D that I'm aware of.

Hopefully that will change soon though.

why a generic battery grip ? the canon one will make the deal.
you can get one for about 150$ and you can buy t2i body +grip for $989.

Third party grips are available for most other Canon DSLRs and reviews have many of them at or very close to OEM quality for less than half the cost.

When it comes to generic batteries, I found out there are two types. One are made with recycled battery cell that can be bought dirt cheap on ebay. They usually won't hold charge after a few months. There're some generic batteries that sold slightly higher in price but still way more affordable than the Canon ones. Those are made with good quality battery cells.

I was actually contacted by a company in asian to resell their cheap batteries. I decided not to go with them and choose the high quality batteries from the same supplier that I'm using.