Personally, I have had the greatest luck growing all of my Paphiopedilum (and some Phragmipedium) in humus... not only is it free, but effective. It drys pretty quickly, but retains a little bit of moisture. It has great benificial fungi that actually grow on the roots of the Paph. and Phrag....

Coconut husk is dangerous for orchids if it is not properly wahed in Calcium Nitrate and Magnesium Sulfate... most of your husk from stores and suppliers is not properly washed.

Also, something VERY good for Paphiopedilum is quartz rocks. They can be small or large, depending on the size of the plant. Quartz rocks give off a nice amount of silicates in the medium. Another needed nutrient is calcium... most common is ground up oyster shell. Ground up washed shell is just as good as ground up oyster shell...

I am done rambling...

Basically, the good mixes are already listed by everyone else! really need a faster, finer draining mix for low-light Paphiopedilum, as the absorbant media will retain water and eventually rot the roots right off here in Florida... Sphagnum can be used in higher-light Paphiopedilum with a courser mix...

-Pat