Have you looked at the QAV Rears ?
QAV BMR I think they are called, they look quite nice, get good reports and are quite deiscrete too, so long as you get the cabling right
For any set-up people often recommend trying to get the same brand of speakers all around to get a more balanced set-up.
As for the QAV (Q Acoustics) I don't think there are many other people that do such a good set-up. See if you can find any second hand going as they are usually < £50, otherwise £80 isn't an awful lot to pay, although it depends on what you and your missus thinks about it though.
Just factor in that rear speakers never seem to do a lot
