The thought is natural toys promote learning and imagination. They are also more environmentally friendly, as they typically are made from substitutable products or at the very least are biodegradable. With their growing popularity do to teaching styles like Waldorf and Montessori, their are more manufacturers and products available. So many traditional toys are readily available like the classic and still popular, stack-able cone designed in 1938

and modern toys like this lab top I purchased from Guide Craft.

As they have regained popularity the price of them has decreased. Big companies like target are jumping on the band wagon with their Play Wonder brand. (Nuriyah's favorite toy is their my first purse set.) However, solidly constructed wood toys will almost always outlast plastic toys. They are the kind of toys your child passes down to their children. What is more is as they encourage imagination they will more then likely be played with longer then plastic toys. (that gain and lose popularity with the fads of the time and achievement of the highest level) When I look at the toys my daughter gravitates to, they tend to be her natural toys like her Baby Stella doll(second favorite toy), handmade iron, and Melissa and Doug blocks. She also sweeps with her broom when I sweep and prays on her prayer rug when I pray. Now that I think of it all of the toys she plays with most frequently were purchased for less then $20.
If you are in the New York area here is a list of handmade toy stores. A list of online natural toy stores can be found here.