I was thinking of making the 50 dollar robot solar powered, because I am doing it in a kindof "green" way.
If that isn't possible, I was woundering is there were any solar powered battery chargers out there.
You cannot get enough power from solar panels directly, since the panel would be way too large.
Solar powered chargers are plenty, Google can help you with that.
I'm also only a tween so it can't cost $100
Twin? Then it should be double that?
Or Teen? I have bought a 3V/100mA solar charger for around $12.
About the I_Wanna_Go_Green part: Don't be too tied up on that. You gotta consider total environmental cost and producing the solar cells probably cost a lot of green (environmentally speaking), compared to what you save (again environmentally) by charging your not-very-green-either batteries every now and then.