Nice, that must have taken real effort. The second hand book stores near here have no proper ordering, so takes ages to find any books. Not sure if the stores your brother go to are any better or not, but I can understand the pain to collect such big series. This is actually why I stopped reading Dresden Files when I originally started, I couldn't find the next book locally, and didn't want to skip any books.
I'll recommend go for new canon books as well. You can always take a break and then continue them later though.