You're right. In general, minimalist shoes are a bit pricy ... unless you do the homemade huaraches or something like that. It could just be economies of scale, though. It's going to be hard to be price-competitive with an $18 billion dollar company, like Nike, that spreads their costs across the sales of about 3 bazillion shoes.
In Terra Plana's case, I think they're trying to make their biggest value not the cheapness of the good, but instead the total "good" of the shoe - eco-friendly, high quality, etc.
TERRA PLANA tries hard to use a variety of eco-friendly materials and innovative, minimal glue constructions. Shoes that are good for you, shoes made from recycled materials, the minimum shoe. The totally sustainable shoe is still a long way off but with each collection we get that little bit closer.
I hope that the explosive growth these minimalist companies must have experienced lately will soon translate into lower prices. Until then, though, I'm going to keep running barefoot and saving the $$Iwould otherwise be constantly dumping into replacing my running shoes. With all that savings Ican easily afford an expensive pair of minimalist shoes!