They purchased 2" thick Spalted Alder lumber, cut it up and glued up to make these great little wood turning blanks.
Many customers are amazed how much less expensive Spalted Alder is than run-of-the-mill Spalted Maple.
$12/BF is a screaming deal for a spalted wood and when you actually set any of these spalted species side by side (Maple, Alder, Beech, etc.), they all look pretty much the same and the biggest defining factor is usually price.
Obviously if your trying to match existing material, staying with the same species might be smart. Yet if all you want is a great looking spalted wood at a realistic price-Spalted Alder may be your answer.