Zaphod, be careful putting merino in the dryer. Unless it is a blend of some sort it will shrink. It only takes one time that the water is too hot or the dryer goes on for too long. Also from a longevity standpoint, clothing breaks down faster in the dryer. I will warm up my woolies in the dryer but that's it. I always have to rescue wool things from my husband's laundry and he's shrunken quite a bit of wool.
And merino does not have to be expensive or bike specific, anything from the gap etc or second hand will do. It's good to have layers and you can be creative too if you sew.