Um, er, ah, in the immortal words of Nancy Reagan, just say NO.
More seriously, I'm not sure what will pacify your wife. Mine has always been pretty understanding. She says that if I must waste money, film, processing, and equipment are better ways to waste it than drink and other women. And I've given up buying bizarremobiles.
Also, she's been a lot more supportive since she's seen me selling equipment. I used to sell via Shutterbug, now sell via eBay. Either way, on average I've done a bit better than break even. Now when I buy something, I tell her. And sometimes I tell her it is a speculation, bought with resale in mind. She lets me keep the profits, except when there are bills to be paid.
Good luck, have fun,
Dan