Well, the places where it's super hard to find a house at 500k, and somewhat easy at 100k, are the border states... New Mexico, Arizona, Texas (and Nevada). In these places, the 500k house is going to be the cream of the crop... the top 1%. Southern California is a different issue, but this isn't going to help the places where the housing market really took a shit, like Nevada and Arizona, because the market there is saturated with foreclosures of homes that might have originally sold for 500k but are probably worth half that much in the current market. The poisonous idea is that these homes were actually worth that much money, but they never were. The artificial demand of the sub-prime mortgage crisis pushed prices up where they should never had been. The 500k limit would try to, again, artificially inflate the worth of the house by stimulated demand in the highest priced homes, homes which should probably sell closer to 350, because the 150k premium might be worth it for some families to get a visa. The second problem with this thinking is that anyone who qualifies for a 500k house would likely be rich enough to get a visa in the US anyways as an investor.

A lower limit of 150k would be reasonable for boosting the middle class, and actually helping the housing market, but that's obviously not the goal.