Maybe you should remind him of what he said to you (re working on the book together) and this being the reason you primarily got the book. I would also explain to him that you would appreciate his cooperation in helping you make savings rather than spending (sorry, i find it a bit iffy for Ts to recommend this or that book and make it seem essential - not everyone can afford to splurge and Ts should be sensitive to that).

IF he continues to be as inconsistent and confusing, could you possibly switch to someone else? I would find it very confusing/frustrating to work with someone like this. I wouldn't know if I could even trust anything they said.