Where to buy Merino fabric?

Hi people, I have just purchased a quilt and would like to make a cover for my S2S sleeping mat and I was thinking merino would be a good choice for the fabric on the top of the mat. I am not sure what to use on the bottom, silk would be too slippery but it needs something as the S2S mats are insanely noisy with nothing underneath.
Would any of you good people know where to buy it and what sort of weight would survive under a restless sleeper? I was thinking 180 or 200GSM. Weight isn't a concern for me but packed size is as everything will be going in to a bike bag and it is not all that big.
Cheers.
Would any of you good people know where to buy it and what sort of weight would survive under a restless sleeper? I was thinking 180 or 200GSM. Weight isn't a concern for me but packed size is as everything will be going in to a bike bag and it is not all that big.
Cheers.