I was always puzzled by the solar panels chargers price tags (sometimes even down to a conspiracy theories). I bought 7 scrap pieces of Powerfilm off eBay several years ago for like 6 bucks each (I was not simply lucky - they were selling them for at least a year or so). Each 2"x5" sheet provides 7.2 Volt x 250mA of electrical energy. 7.2*0.25*7 ~= 12 Watt (when connected in parallel). Everything for just $40. They are much more flexible and compact than anything I saw on the market (so compact that I'm EDC'ing them like 90% of my active time).