All other factors being equal, late summer/early fall, is the best time to expect lower prices, especially for sellers who have had their homes/condos for sale for a while. It is interesting, that in this buyers' market, many sellers are willing to negotiate much lower than their listing price, but won't actually lower their listing price. So be certain to work with an agent who knows the area you are buying in and can help you determine the best value for what you want.
Having said that, there are motivated sellers any time of the year. Sometimes you have to make an offer to fully evaluate the motivation of the seller. In general, the longer a listing has been on the market, the more motivated the seller. However, I have had sellers price their property to sell immediately and recently sold a home in 2 days because the seller was extremely motivated and priced the home accordingly. Similarly, I have worked with sellers who would like to sell, but are willing to wait years to get the price they want. There are just so many variables. Regardless, this is definitely the time to buy.