A question comes to my mind over and over: in many cases, actually you must buy the font and prove it by yourself to be sure if the font is really what you need. And it is very frustrating when not. IMHO, text samples in PDF are poor substitutes of “the real thing”.
What are the type designer/vendor options? To offer a demo/free font, with some (important) glyphs missing? Some kind of devolution policy?
And what are the user options? To buy a single weight, prove it, and only buy the complete family if it works fine? To check if some friend already has the font, go to his/her computer and prove it there?
Any thoughts welcome.