I think if it's to live in, AND you can afford it AND it makes sense financially on a fixed rate mortgage, go for it. You are absolutely right on market timing, but that doesn't mean it'll go up forever, but over time, it does seem to generally go up a bit. But it's not really an investment, its a place to live, so don't pay so much on a mortgage that you are risking your financial health - think it should be about equal to rent or maybe a little more.
Just remember, turkeys think everything is great, until Halloween, when they get put in the freezers for Thanksgiving. If you look at the graph of their weight from birth to death it's always going up, so it should go up forever. But on Halloween it'll go down a bit, then level out forever. ;)