Sometimes when you work at a company, you just can't walk into Joe Bobs Computer store, and buy up a thousand license for your dells. Nor can you walk up to Mr.CEO and get cash. Sometimes you have to deal with purchase orders, ect, ect, and since you already have a working relationship with Dell, you can order your license through them, and since you are already a customer of theirs, they can give you a discount.

here's the contact info depending on what size your company is

Global Enterprise Business (over 18,000 total employees) 800-274-3355
Medium & Large Business (200-18,000 total employees) 800-274-3355
Small Business (fewer than 200 total employees) 800-274-3355
Business Employee Purchase Program Service & Support 800-934-1652