yeah, you're on the right track! so, there's a 1/6 probability of rolling a 1 (and losing 3 bucks), a 1/3 probability of rolling a composite (and winning/losing 0), and a 1/6 probability of winning each of 2, 3, and 5.
So... the expected value would just be \(\dfrac{1}{3} \cdot \$0 + \dfrac{1}{6} \cdot (\$2+\$3+\$5) + \dfrac{1}{6} \times -\$3 \approx \boxed{1.17}.\)
hey, that's pretty good!