Take a look at my picture when I rode with the Historian.
Brightly colored, with reflective panels in case I get caught in the dark. Moisture wicking, and even though I was a little warm that day, they do also come in a short sleeved version. They also have a light windbreaker that I bought, but haven't worn yet.
These are available in either ANSI Orange or ANSI Lime. I could particularly tell the value of the wicking after one rest stop... when we took off, my arms felt very cool as the wind passed and wicked away the small amount of sweat that had accumulated while sitting.
The short sleeve without the reflective panels are $9.95
http://www.AlertShirt.com