Lots of stuff to buy!
There's Bang, it's a novel about a woman named Sandra and the end of the world. Sorta.
Of course, if you don't particularly care about the physical copy, and just want to read them, you could sign up to be a Patreon patron, and you'd get access to the pdfs at no additional cost!
There's also shirts and prints through Cobalt Pulsar. Right now, they're just Leftover Soup-related stuff, but I may create some Forward-related merch there eventually.