If you are planning a large orchard (50+ trees), these commercial-focused suppliers offer significantly lower per-unit prices: Where to Get Rootstock For Grafting - Salt in my Coffee

For most hobbyists and small-scale orchardists, the consensus for buying grafting rootstock centers on a handful of specialized nurseries known for variety and quality. Top-Rated Online Nurseries

: Known for a massive selection of unique fruits. They sell rootstock in bundles (e.g., 5-packs for ~$25) and are noted for high-quality, though sometimes slightly higher-priced, materials.

: Highly recommended for beginners because they often match the diameter of their rootstock and scion wood, which simplifies the grafting process. Commercial & Bulk Suppliers

: Widely considered a gold standard, especially for apple and pear rootstock. Reviewers appreciate their "insanely huge selection" and the ability to choose specific rootstocks for various soil types and tree sizes.