I bought mine online from Advanced Tree Technology several years ago as a bareroot four footer. At that young age they are not white, though. It did take about 5 years to become a 10 foot, white birch.
We had a very hot spring & summer this year, and it seems fine. I did plant it on the edge of a forested area because I read birches live in that kind of situation. I put Bayer Advanced Tree & Shrub systemic insecticide on it once a year to kill any birch borers that may be lurking. So far, so good.

Out of curiosity, I checked the price on Forestfarm on a Renaissance Reflection. I believe the price at Advanced Tree Technology is better, a 4 ft. one costs around $41 including shipping to where I live in Virginia.

I'm guessing you should be able to locate it at a nursery in your region. I believe Beaver Creek Nursery (Chicago area) grows it, and they may be able to direct you to a retail source. I have seen one of the original test plots for this variety (in OH), and it is an attractive tree with a high level of resistance to BBB. Worth seeking out. See link for add'l info.

Here is a link that might be useful: patent for birch tree named ?Renci?

Does anyone know of a nursery that ships and has Renaissance Reflection Birch in stock?