User Review: Mountain Hardwear Butter-Man 1/2 Zip
Price Paid: $65
I agree, this shirt is as smooth as butter. My wife was so jealous of how soft and comfortable I had to buy her one.
I run a lot and I would say that it is the most breathable item of clothing I've ever had and I have several drawers full of synthetic running, backpacking and biking clothes. The fit is excellent and they did a great job of seam placement to prevent chafing as you sweat.
I highly recommend it!