Your post sounds really bitter, OP.
I do a ton of research and put a lot of thought into everything I need to buy; then narrow the list down to a manageable level; explain pros and cons of each to DH; bullet point why I have a preference (if I happen to have one); then let him voice an opinion.
If he picks something that really doesn't fit with my scheme, I work to persuade and convince him until he changes his mind.
Basically I research the stuff to death, present objective, rational arguments, and wear him down. That's a winning combination for any topic of discussion