My strategy is a little different. A combination of glasnost and need-to-know.
"It broke. I'm fixing it." and it's corollary: "It's a spare, for when it breaks." (This is when he finds stuff, or there's new packages I haven't hidden in time).
And "I bought a new fan."
"That's nice."
(Not realizing we're not talking about a $14.99 window fan for the house.)
"Do you think the carpet needs replacing?"
"Uh, I dunno. Whatever you think. It's up to you."
(Yes, I replaced it, got rid of the stock beige/bone color and had a silvery grey done instead...and it does look great!)
"I'm thinking about a head job."
"YEAH!"
"Mmmmhmmmm.

"
And if he gets all pissy because he found something he recognizes as new AND expensive, and knows what it is...
"But darling, YOU bought that for me, for my birthday last year, DON'T YOU REMEMBER????? What do you mean YOU FORGOT and YOU DON'T remember buying me that??? Now isn't that something you WOULD HAVE bought me? Then what's the difference???"
Heh.
Different strategies, of course, but I will remember the shell game one, thanks. Too bad I suck at the accounting game, but maybe I can bluff it.
Or I can simply resort to my old standby:
"Yes, I bought it. SO WHAT?"