I magine if you take cuttings from the wild, or your friend, and get them to root, that is great. When you plan on purchasing them, where would you recommend going? Is organic an important consideration, meaning care with soil amendments and no chemical sprays/fertilizers have been used?
The cheapest I've found are from a company that seems super shady, so I don't even want to reference the company on here because I don't think THEY even know what variety they shipped me even though they had different varieties listed on their site.
Although they only provide rooted cuttings of elderberries, Fruitwood Nursery is a good place for scion/cuttings of basically any sort of fruit species.