To get decent prices on solar panels you have to pick up from a local supplier (which at least here in the US is difficult because they cater primarily to professional installers); they're just too expensive to ship. Even then around here the cheapest panels are going to run at least ~$0.35/W, although you might be able to find used ones for less.

Batteries are a little easier. For used in the US I'd take a look at https://batteryhookup.com/