90430 is a code for a free month of 3 out at a time, unlimited in-store exchanges, 1 free movie/game coupon, and $19.99 a month after the first month (more benefits than the $34.99 plan for nearly half the price).
If you use a prepaid debit card with not enough $, or Paypal's Virtual Debit card, Blockbuster will try to charge your account for another 2-6 weeks, while still shipping out movies, before they cancel your account (extending the trial even more).
Easiest thing is to do the trial method, and cancel right before the trial ends. If you change your billing address, you can use the same card again for another free month trial. Rinse & repeat. I've been doing this method for a combined 15 months now (6 months now, 9 months a few years ago).