While I'm not sure on any actual numbers here, I'd have to say that odds are he'd be getting anywhere $0.75 to $1 a unit.

At a retail price of 10 dollars, you need to factor in the retailers buy it at wholesale to make their profit. So they are buying it at $5-$7. Now the materials and such to produce the actual physical product; box, art, disc, etc, I could see easily being $1-$2.

We'll take the lower profit number (I always under-estimate when it comes to profits) soooo.... :

$10 Retail Price
$5 Wholesale Price
$3 Profits after Manufacturing costs.

We'll subtract around 75% (guess-timated) for publisher's percentage.

$0.75 per unit profit for Author.

33,000 units at 75 cents a unit is 24,750 in pay.

I could be wrong, but it would seem likely to be something close to this. I'd love to be proven wrong and hear he made more...

It'd be interesting to hear what kind of deal he got, just to have something to compare to.