Don't buy it now...wait utill the sellers list the property with me as their agent, then buy it. ;-)
All joking aside, though..If you are asking about a property in Villanova, you need to look at statistics local to Villanova. Prices in the 2nd Quarter of '07 have dropped by 12.67% compared to last year. The average sale price in Villanova (zip code 19085) for the quarter was $1,085,400, and the the average sold price was 94.8% of the asking price.
Looking county-wide, the 2nd quarter average sale price increased compared to the previous quarter, and the projection is that it will increase in the 3rd Quarter also.
So, to answer your question...I need to ask another question: When prices are down vs last year, but up vs. last quarter, and (projected to continue to rise), what is your risk comfort level?
Looking at a 25 year rolling average, Real Estate values appreciate on average at 5.4% per year. (National average -- it could be more or less in certain regions.) You need to evaluate whether it "makes sense" or not based on your specific goals and specific financing options. You may only be putting 20% of the purchase price down, out of your pocket, but any appreciation will be based on the entire purchase amount. The longer you plan on staying in the home, the less risky the fluctuations in the market will matter to you.
All in all though, with the large number of homes on the market, and mortgage rates near all time lows, you could do much worse than investing in a home now. Keep in mind, though, that a home is not just an investment. It is a place to build memories, to enjoy life with family and friends. If the home is right for you and your family, and you can afford to live there, I echo the "Nike" slogan -- "Just Do It."...with me as your REALTOR ! ;-)
(The reference link is to the Regional Market Report for 2nd Q 2007)