I used to buy sleeves of the smaller deli cups and lids from Albertson's in the deli department. You can purchase a small size hole puncher ar Office Depot for punching airholes in the cups.
These days we order all of our deli cups and shipping boxes online from a company called Superior Enterprises. Their prices are very reasonable and the deli cups come pre punched with airholes. You can click on the link below to access their website.