Icebreaker or Rohan merino is the best you can get. There has been some Icebreaker stuff on sale as they changed their product range / styles. Otherwise I tend to wait for the Rohan sale.
Unlike some of the cheaper brands it you shouldn't itch and it will last for years. Still regularly wearing Rohan merino baselayer I bought for going to Norway in 2006. The heavier 200 weight as a winter base layer and the lighter 150 weight is great for summer use even at 20 degrees+