I just looked; there are sets available online for a few hundred dollars. Apparently they’re popular with homeschoolers now.
Nostalgia’s all very well, but I have better things to do with the money.
Most of the old stories were morality tales, and the ones harking back into Europe are supportive of Western Civ values, so those books still have value for patriot families who read to their kids. Homeschoolers often have associations with other families to offset the cost.