1- One of the most reliable places to get genuine Volvo parts at a discounted price is a salvage yard. This might not have been the first thought that came to mind when you discovered that you needed to replace a part. However, salvage yards cope with factory parts that are still working even if the car that is original not. Many salvage yards operate on an "as is" basis, but they also depend on their reputation to stay in operation, they test parts before putting them up for sale. This is an option that is excellent you are looking for something like a cooling fan or a windshield wiper motor.
2- Searching the internet can yield excellent results when looking for discount Volvo parts. This is what most websites specialize in, quality parts for less. An added bonus of internet sites is that they can also offer reviews from previous buyers, installation instructions and forums that are filled with other enthusiasts who are more that willing to answer your questions.
3- A more hands on way to find the parts that are discounted you need is by going to auctions. An auction, specifically a car auction, is a great way to find the parts you is looking for as well as a great way to obtain them for a price that is good. Another advantage to the auction is that you can physically handle the piece and talk to the seller to get an accurate history.
4- A close cousin to the auction is the swap meet. At a swap meet, there will be a number of other Volvo owners. These owners are looking to get rid of certain parts and accessories, sometimes for money, sometimes in exchange for parts they might need. A swap meet allows you the luxury of speaking with the owner and holding the part as with the auction.
5- The most place that is obvious not likely to be a good source of discount parts, but it never hurts to check. The dealership will be able to get you the right part you need, even if its at full price, if your other options neglect to produce the part you need.