Amazon offers Prime members 3-D Rarities on Blu-ray for $24.95 with free shipping. (Non-members can spend $35 or more to qualify for free shipping; otherwise, shipping costs $4.98.) That's the lowest total price we could find by $15. It includes 22 restored classic 3D films, a handful of essays, and commentary tracks.
Note that although Amazon is now temporarily out of stock, it can still be ordered at this price for delivery when available.