In the case of the IT Professional or anyone who sells the same thing at the same price to their client, there is even a faster way to do this.
Set up an item or product/service for the expense. Then every time you purchase the same item you can just type the name of the item and all associated information will pre-populate. If the purchase reoccurs on the same day each month you can even save it as a reoccurring or memorized transaction so it automatically posts. The memorized transaction will hold all the necessary information including expense account, amount, description, mark-up percentage, transaction amount, and the client responsible for the charge.