Two important things (1) there are only subscriptions (2) there are many counterfeits, low prices are probably fakes; there are no margins for resellers to cut. Adobe do sometimes have opening, one year offers but this isn't likely to help an educational long term strategy much.
Warning, scammers may contact you privately pretending to be Adobe staff. Adobe will never send you a private message asking you to email an account that isn't @adobe.com, or use Skype. Adobe never ask you for their password. These scammers want your Adobe info, credit cards, your money and control of your computer, please take care.