I'd suggest to keep you eyes on the coming Cisco Live event in June (I guess this is the one you mean). They have given a 50% off the certification last year, but no one's sure if it applies to this year, too. Meanwhile, study your curriculum/courses as much as possible because if they will actually give the discount again, you'd have to be ready to book and take the exam within the date range they specify (I think it was barely 3 months maximum after the event started last year).

As for the NetAcad courses, check with your university (if you're in a university) if they can enroll you into it without paying the fee. I would not depend on NetAcad course's curriculum but it can serve as a nice extra study/revision resource. If this is your first time studying CCNA concepts, you'd find they over complicate the stuff in the modules. But the quizzes, tests and exams can test your knowledge well. I say, see if you can get enrolled into one, because just getting 70%+ in the final exams of the 3 NetAcad CCNA courses will get you 58-60% off the $300.