I bought two (too) cheap chargers and battery using ebay from HK last year. I tossed them nearly immediately after receiving them, because:
- The chargers were extremely dangerous the way the wall adapter was constructed (and how the euro adapter was fitted over it, having an abysmal build quality). I didn't want to risk my life. The 2nd charger even had a missing contact.
- The batteries were counterfeit: while they looked exactly like the Nokia ones, they were much lighter (!) and had their own brand label - but once you pulled of the label, there was a Nokia imprint underneath it, blacked with a Feltpen...

Experience: brrrrrrrrrrrrr.