The reason that you will find multiple units "sitting" in any community is a function of price. Three of the 4 townhouses currently for sale in Downingwood have been on the market for over 4 months. One of them has been reduced over $100,000. The truth is that it was overpriced to begin with.
I am currently selling a unit in Fieldpoint (another Irvington development) that went in to contract very quickly. Why? Both seller and buyer were reasonable AND realistic.
Make sure that you work with a realtor that work for you and do the necessary homework.
I live in a condo development very similar to Dowingwood where Birch Lane is located. Every complex goes thru cycles. People are relocating, buying larger units or homes or numerous other reasons. To the best of my knowledge, there is no particular reason why now there are many units on the market. Obviously, it is advantageous to buyers.
Finally, if you are going to purchase a unit in this complex or any other, you and your attorney would have the opportunity to look at the complexes financials and also receive information via your realtor as to any current and potential future assessments for capital improvement projects and possible increases in the common charges before you sign any purchase contract.
If you have specific questions about this complex or other, I look forward to answering them for you.