Buy from Ebay. They take a while to arrive (maybe 3 weeks), but you can get an original new battery for less than R100. I've bought two this way. Or you can try bidding on one (I've bought from this seller before).
Dunno if I can wait that long
My phone doesn't last half a day so I have to take a charger with me to work every day and it's a huge hassle. I can literally watch the battery percentage drop around 5% while I'm using it about every 10 mins.
Usually the BTU roms work fine with no vodacom bloat