It's $166/head counting every person in the area affected by the earthquake, and $2000/house counting all the houses destroyed by the earthquake. Most Haitians did not lose their homes to the quake.
Habitat also estimates 105,000 "totally destroyed" pre-quake houses.
Obviously, all of these numbers are better than the six houses the Red Cross built.
The larger problem in Haiti is legal, though: getting the rights to land to build on is complicated and slow.
Haitians aren't looking for 2-car garages and island kitchens. Running water, electricity, and a structure that won't collapse in the next natural disaster would do just fine.
I imagine a challenge with deploying manufactured housing to Haiti is that anything new that's built needs to be earthquake-resistant.