I'd say easily <$300 for a ~100W solar charging system if you DIY. If you build for expansion, it might be worth spending more for nice fat wires and a higher capacity controller.
solarblvd.comdarvex.comI'm not affiliated with those sites at all, they're just where I bought some of my stuff from and I'd say they have good prices.
I agree that OP should start out with addressing battery capacity first. Sounds like he already has a nice generator. Maybe look into the onboard converter and make sure it is a nice 3-stage smartcharger. That way he can make the most out of the existing generator. I'm all for solar, though.
