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I used the first edition of Alison Raju's guide, then quite old but still very useful when I walked this route in 2012. A newer edition is now available, but might be starting to suffer the same way. Whether it is best or not is difficult to tell.
You might find that a combination of resources will be more useful than a single guidebook. The Norse pilgrim site has good maps, as well as up to date information about accommodation, and you will find other resources on this forum and elsewhere.
There is adequate accommodation. I have no idea what you think might be cheap, but you would be walking in one of the most expensive countries for travel in Europe, so don't expect it to be the same as pilgrim routes in southern Europe.
Here is an accommodation list from the official Norwegian website. It should give you some idea of the range of accommodation and prices. "Cheap" and "Norway" do not normally belong in the same sentence unless accompanied by "not"