Mary and Joseph and real estate

OK, so it has been a while. I will endeavor to be more prompt in my postings in 2007.

First place, happy new year. May 2007 be a good, blessed, and prosperous (in every sense) year for you and those you love.

A few thoughts prompted by the season.

According to Luke 2.24 ("And to offer a sacrifice according to that which is said in the law of the Lord, A pair of turtledoves, or two young pigeons") Mary and Joseph offer the poor man's sacrifice for the firstborn child. (Leviticus 12.8: "And if she be not able to bring a lamb, then she shall bring two turtles, or two young pigeons"). So we may safely assume that Mary and Joseph were not wealthy.

However, approximately 2 years later, when the magi appear, the holy family is seen living in a house (Matt. 2.11: "when they were come into the house").

My question is: what changed in Mary and Joseph's economic standing in the 2 years between Jesus' birth and the visitation?

Joseph is traditionally remembered as an old, if not elderly, man, so we might assume that he was in his years of economic decline, not on the upswing.

And while we can guess that the gifts of the magi were an economic boom to the family, or at least a bit of security for them, the living in a house is prior to that.

What I'm wondering is if someone can guide me to further information about housing conditions in first century Palestine. Does living in a house in Bethlehem imply that they owned the house? Or were there rental houses for folks then?

Even renting seems to imply some economic stability, if not comfort. So I ask again: what changed? The one thing I've considered is that Joseph might have been relatively comfortable financially, but that perhaps the registration, census, and taxing (in Luke 2.1-3) might have strained his resources, so that the family was temporarily poor, and that in the next 2 years, they had financially stabilized, hence living in a house.