Believe it or not, after years of searching and a few attempts at making my own, I have found the ultimate mouse mat.
What I am using now (I shit you not) is a car floor mat! I know it sounds weird, but it works like a dream.
size: 60cm x 40cm,
sensitivity and accuracy: feels perfect
surface is smooth and soft on my hands 
£4.99 is the price for 4 mats, less than £1.25 ea.
havent found a downside yet.
what mat do you use? how much did it cost? have you ever used anything other than a purpose made mouse mat?