Alright: here's the deal. Get an expensive habit. Starbucks is the most socially-accepted drug habit, but I'll leave that up to you.
Then, after your wife gets used to watching thousands of dollars a year going out the window, suddenly stop the bad habbit. But don't stop taking the cash out of her purse. Do that part still. Only, put it away for your spa. (The money, not the purse).
Could be yours in 10 months if you drink Venti mocha blended with a double shot and whip. Or so I've heard....