Final answer:
Products that you can only buy through Scholastic and not through third-party vendors are called exclusive products. These can be popular textbooks with high student demand, which often leads to quick exhaustion of supply.
Step-by-step explanation:
Some products that you can only buy through Scholastic and not available through third-party vendors are referred to as exclusive products or exclusives. These items are only available for purchase directly through the company's own channels, such as their website or catalogues. The exclusivity often makes these products more desirable and can sometimes create a sense of urgency for purchase among consumers, especially when dealing with popular textbooks. It's common for these exclusives, particularly sought-after educational materials, to experience a high level of student demand, which can deplete the available stock more quickly than less popular items.