Cheap microfibre cloths
 

From Tesco, 99p for a pack of three. Haven't tried them yet but they are a bargain. Smallish so brought nine.

whoa i thought the asda £3 for 3 ones were cheap :-(

I buy them there too, and in quantity every time they're on offer, also the 99p applicator pads (3) and the alloy wheel brushes and microfibre cleaners (99p)

they wash up really well in the washing machine too!