Merino wool is wonderful and wish all my clothes were made of it. I'm getting there. I got some second hand merino wool sweaters a few years ago and was hooked. I live in the pacific northwest where it is always damp but my lambswool sweaters were too itchy to even contemplate. Way better than cotton or synthetic! Perfect for summer and winter and everything in between. May I plug cashmere as well? Like wearing kittens. I find the fancy schmanzy merino jerseys at high end bike shops very itchy. Rivendell(rivbike.com) sells a great selection of merino clothing at decent price as do most bicycle clothing online stores. I am a big fan of Icebreaker which costs the earth but it's so soft, wonderful, and lasts. Icebreaker is big on marketing and being sexy, but I love the stuff. I have a pile of it. I buy it on sale and on ebay. If it has so much as a snag, it will be on sale. I have not heard of Rapha! Smartwool makes merino activewear and is okay. Ibex is an american company that specializes in merino and has oodles of cycling stuff plus new merino knickers for men. Made in the USA. All kind of pricy. But if you are looking for a merino sweater check out the gap or other such stores. In the winter they bring in cheap merino sweaters that quickly go on sale. I also scour second hand stores for merino sweaters etc.. I can fit into sweaters that have been shrunk.
Just don't put merino in the dryer!