The email should include a list or link to your desired items and the business reason for the request.
Example: I would like to purchase the Bose QuietComfort Noise Cancelling Over-Ear Headphones in blue. These headphones will be used for my online courses and to assist with concentration while grading assignments. Link to Product
Examples of items often requested for purchase include books, tablets, supplies, software, memberships, publications, journal submission fees, subscription fees, office supplies, etc.