Bflowers, you are looking at deception only from the positive form - actually speaking something false. There is also a negative form, a passive form, which involves withholding information. It is just as problematic. A person who withholds requested information is wrong to consider himself as not having lied just because he kept from stating something false.
Hence the stuttering, as it would be in your mind a "lie" to state something misleading. But you may want to withhold critical information and justify that as not lying because you didn't actually say something false.
"She may ask..." means she has asked and you have balked, knowing the information would not be taken well.
Withholding important information from the spouse is a passive form of lying. It usually requires a list of justifications in the mind.
A man is either going to be straight with his wife or not. Being straight/transparent means she knows the truth about what SHE wants to know when she asks, not what you want her to know. And you won't have to stutter for more than a nanosecond.
Your wife must love you very much. It seems she sees you struggling with it, not wanting to actively lie and she drops it so as to ease your conscience, and also likely she may fear what money is being spent. My guess is she knows the equipment costs far, far more than she would ever want to be spent on it. It also seems she's not given a say in the matter, and it's likely this bothers her. Over time that can build resentment. You may find it very productive to discuss the issue with her.