I've found Maplin to be cheapest and while they used to be in a time-limited offer, they're now reduced to this price - no time limit.
I have some for the wii remotes already but wanted some more for when all the cousins arrive and there's a fight for working remotes.
Charges AA, AAA or PP3 size batteries
Includes 4 x 2100mAh NiMH Hybrio batteries
Convenient plug-in design avoids trailing leads
Automatic shut-off timer