[quote author="ipoplaya" date=1222604861]So Columbussquare, if one can afford to buy now, but prices are falling and will continue to fall for at least a short amount of time, why buy now? Affordability notwithstanding, why make a purchase of an asset when it will be cheaper next month and even cheaper next year? Would you buy a new car if you knew you could get it for 10% less next year? Most prudent people would milk their existing ride for a few more quarters and wait to get that shiny new car for cheaper later...</blockquote>
While purchase prices have been dropping there is no guarantee that relative prices will go lower. The relative price includes the impact of both financing and taxes.
For example a $500k house could "drop in price" by 1% (or $5,000) but it could actually have an increase in the relative price if the net effect of an interest rate change is greater than one discount point. So an increase in interest rates by say 0.50% (or two discount points in this example) could actually cause relative prices to increase by $5,000 on a $495k purchase (because it cost $10,000 to get the same interest rate as when the price was $500k). The uncertainty in the financial markets, and the failure of multiple banks, could mark the end to the "historically low" interest rates. If rates increase faster than prices drop the relative prices will go up.
Another example, would be where someone pays an additional $10,000 in federal income taxes while saving on rent. Rental rates should be adjusted for taxes to provide an accurate benchmark against the "cost of ownership".
As a balance to your new car example, you might do the research and determine that there is a 70% chance that the cost of the new car that you're considering purchasing will drop. However, if you need a vehicle to get to work, or as a component of your job, you might still purchase it today for the utilitarian value. Even if your existing car is functional, you might value the enjoyment of the new vehicle over the year more than the financial savings that you would realize if you waited.
Location is another factor. By moving you might realize savings of both time, gas, and vehicle wear by being closer to work.
Availability might change in a year and you might not get the exact property that you want. That might warrant paying a "premium" today.
The best time for you to buy, if you can afford it and choose to do so, is when the situation makes the best sense for you. It's possible that the known savings in taxes, gas, and time might overweigh the unknown profit (or loss) that you'll incur from a change in prices or financing options. If you have a sustainable long-term purchase then it won't matter that much at the end of the day if you buy today or tomorrow. If you were to wait, the risk is that it might not be sustainable in a year and therefore unattainable. If you were to act now, the risk is that you might not make as much money as you would had you bought at the bottom.
I can give you examples of people who have bought at the top and at the bottom and many points in between. More often than not, it's the long-term plan and micro-economic focus (i.e. your situation not the rest of the world) that works best.