Amazon offers Robotech: The Complete Original Series Set on DVD (with a bonus disc) for $39.96 with free shipping. That's the lowest total price we've seen for this 20-disc set by $15. (For further comparison, we saw the set without the bonus disc for $7 less last summer.) It features all 85 episodes, The Shadow Chronicles film, Love Live Alive film, and a bonus disc with two documentaries.
Don't mind picking it up? Walmart charges the same with Site-to-Store.