Would like to see from experienced rehabbers whether you buy materials yourself versus having the contractor supply them...

If your buying,  is it worth the extra effort to control the cost and get exactly what you are envisioning.. 

Or, if contractor is supplying, how specific are your instructions for what you are requiring?  Eg:  Here's a picture of the tile/flooring I would like and they come back with something not quite what you had envisioned.