We're halfway through, so it's about time I did a quick rundown of my sources and other useful info.
Campsites
I looked for campsites in three places.
The most useful of them is the official Icelandic tourist site. It has a ton of other helpful info, too. Another solid idea is to drop by the infocenter in Reykjavík, they have tons of brochures there. Campsites, as I wrote before, cost around 5 Ls ($10) per person. In the wild places where there are no utilities, they charge another 2.5 lats for electricity per device, and the same amount for a five-minute shower. At campsites, aside from Landmannalaugar and Thingvellir, there usually isn't any way to wash and dry your clothes. You can also only buy gas or groceries in Landmannalaugar.