I visited a few bike shops today trying to get a 29er rear crud-catcher.
First shop only had the front and rear combo packs, second had none. My last port of call was Exmouth Cycles, and whilst they only had the combo pack, the guy offered to split it and sell me the rear, and then only charged me the same as the standard rear mudguard.
So, excellent service and friendly, helpful staff.

*round of applause*