Every carrier offers employer or education specific discounts. You should call your carrier & ask if they have discounts if you work for a specific company, industry, or attend university or are part of an alumni association.
Back in the day when we were on the $30 Sprint SERO plans, they were dumb enough to stack the sero plan (already discounted as a sprint employee referral/kind of like friends & family of Sprint employees) with my employers 15% off discount. For 3 years I was paying $25.50/line until they started auditing all accounts & removing discounts. Now on sero premium for $50 with an iPhone which still isn't bad compared to the $80-90 I'd pay on AT&T or Verizon with similar plan features (500 anytime, free nights/weekends & long distance, unl data, text, pix, etc).. Sprint sucks but it's cheap.