I love this tree. It is also called the wedding cake tree as the branches appear in layers and the foliage and blooms give it a creamy color. You did not mention where you live but in most part of the USA you can order this tree at your local nursery and they can find if for you from a wholesale grower. I have also seen it for sale at Lowe's so you can try pre ordering one from them or ask the manager to alert you when they get one in stock. I have also seen seeds for sale on Ebay but I do not recommend buying tree seeds online if it is not from a reputable nursery. This variegated dogwood is worth the hunt and by calling local nurseries now and offering to pay a deposit in advance you may be able to get a tree in time for spring planting.  You can also wait until fall to add this tree to the landscape but order it soon as it can have months to have the tree brought to a local nursery from a wholesale grower. Keep growing, Marianne Binetti