E.L.
I have some girl scout clip art which I can send to you if you contact me offlist. I was a Br ldr for two years in a large troop in another state and we did a troop tshirt like this: I bought blue ones to coordinate with their brown sashes or vests. I drew a simple flower, big petals, with fine pt sharpie marker. They picked paints of their choice to do the petals and afterward they painted glitter pt over the dried petals. They looked great. We also had a mom write "Girl Scouts" on each shirt after they'd painted it, in calligraphy toward the bottom right of the image. The girls LOVED painting their own, but because the design was simple it was nice to have them look similar to each other but not *exactly* alike. They also remembered what the colors stood for easier because they picked which 5 or 6 colors they wanted to make their petals (using the gs colors from the Daisy GS petals as a basis of selection--creative outlet and educational!). This also fulfilled an activity in one of the Try-Its.
Another leader told me she had the girls pick out which GS color they wanted their handprint to be, and each of them put a handprint on the troop's shirts. After they dried then a fine pt sharpie over the hands for their names. I think that would be the most awesome troop shirt because it would really mean more than any fancy screen-printed one. You could have the girls vote on it.
Just remember to wash your tshirts in warm or hot water first and tumble dry them and iron them really well. Then they'll last for years and the girls can have good memories everytime they wear them. Have an awesome year.