Prices of Materials

I've been collecting prices from a bunch of Montessori suppliers for various materials. It's amazing how big a price range there is for some products. For example, the least expensive Hundred Board is $22 while the most expensive is $166! Here's what I have so far:

Constructive Triangles
Continents Globe
Golden Beads
Grammar Symbols
Home Country Puzzle Map
Hundred Board
Large Bead Frame
Long Rods (Red Rods)
Multiplication Board
Multiplication with Bead Bars
Mystery Bag/Box
Number Cards
Pink Tower
Sandpaper Globe
Small Bead Frame
Sound Cylinders
Stamp Game
Trinomial Cube
World Puzzle Map

I have no idea what sort of variation in quality there is between all of these. I could see it mattering with things like the Puzzle Maps, but the Number Cards shouldn't really make a difference. I've seen plenty of official Montessori classrooms with Number Cards on laminated card stock.

Subject Areas

One thing we could use more of in schools is an understanding that real life is not neatly divided into separate subject areas.
Just the other day I was reading a book about the history of the scientific method as applied to medicine. In which subject would you find this wonderful book in school? I was reading a book, should it be in English class? It was a history book, so should it be in Social Studies? The book was about science though, should it be put in Science class?
The answer, sadly and simply, is that you would never read something like that before you got to college. You wouldn't see that book at all because there isn't one clear-cut category in which it would fit. Standard K-12 education is uncomfortable with books like that.