Out of my comfort zone

I'm going to do a Mystery Quilt in March (a one nighter) and I have to have 3 rectangles from 38 different fabrics. I thought maybe I'd start using some of my batik stash .. (this is about 2/3 of my batiks) but I never find colour's easy to choose. I think I'll have to play with these for a few days rather than start cutting straight away. At least the rectangles are only 3 1/2" x 6 1/2" so if I have to buy some it won't cost a lot.