My wife doesn't ask me if I'm selling any of them anymore. She considers them dangerous but is able to understand the obsession (now). You must always be on your game to train a woman correctly about YOUR motorcylces. never show weakness, show enthusiasm that they are interested in your machine, tell her EVERYTHING that you know about it , what you love about it, what you don't like about it, what you are going to change about it, how this change will effect the overall machine...... do this in one continuous sentence with no breaks, no interruptions, ....after hearing something like that , if done correctly ,she'll be late for that reality show on the TV in the other room and will leave you in the garage as fast as she possibly can. Don't forget to blow her a kiss as she's heading for the door. That way she'll know that you care and her jealousy for the machine will diminish over time.
When I'm out working on bikes and someone calls , she says "He's with his mistresses, I'll go out and get him". I stopped answering the phone in the shop , whatever it is can't be as important as what I'm doing to a bike at the time so , no answering random phone calls anymore for me.
If my wife asks what's in the box , I'll show her, explain how it works, the condition of the last one compared to the new one ,how much better this one is , and how happy you are about it .... a few times doing that and she won't ask you the next time a box shows up at the door.
Cost? How can you put a price on it? Are you kidding? This is an intricate part of the total machine , and without it, the entire machine ( this investment) would be worthless. Then you can tell her how much it costs but you got a great deal because usually that part is so much more...I couldn't believe it either (look excited) Don't forget to blow her a kiss as she's backing out the door. Everyone will feel better about the whole thing.
Well, now you know some of the tricks , look serious, don't be cross, smile when appropriate , make sure she feels like she's an important part of your life and remember ....She needs to feel that she is more important than your motorcycle... don't forget to blow her a kiss (or equal) .And one day this stuff won't be an issue, it'll seem so natural and you'll both feel better about it. Good luck.