used canon LP-E8 or Watson 3rd party?

I'm looking to add a backup battery and shopping at B&H. For now I need to keep the cost as low as possible, does anyone here has experience with the Watson brand batteries? They also have a used 9/10 Canon OEM battery for $30. I'm just wondering which might be the more prudent buy. To me Canon OEM, even used, is a better bet than aftermarket but would love some input.
Thanks!

3rd parties can be had on eBay for about $8. As long as you watch your MAH (and don't buy ones that claim to be Canon), you should be fine. I use them in everything. No way I can afford to pay Canon's ridiculously abusive prices on batteries. I am pretty sure they're making 95% profit off of OEM batteries, and its not worth it. 3rd parties work almost just as good for a fraction of the price; just watch out for counterfeit Canon's, and make sure to get undecoded ones so they read battery indicator levels.
(I'm much more scared of ones that claim to be Canon's, than I am of ones marketed as third party batteries.)

I've had nothing but luck with Wasabi batteries.

I never buy any OEM batteries; waste of money. 3rd party function just as well if not better (some have higher capacity) provided you go for well known 3rd party brands, and not fakes as Darin pointed out. In the US I believe Sterlingtek and Wasabi are the best. I'd take a new one of those over a used OEM any day. You never know how used batteries have been treated e.g. overcharged, poorly maintained etc...

Thanks! I ordered a pair of Wasabi's and a charger for the car just in case, from Amazon $21. not a bad deal.