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.