Most FF have 0.8 pitched gears but there are other variations as well.
Regarding price, of course most of the time you get what you've paid for. Nonetheless I think that new manufacturers brought great products at a reasonable price/performance ratio recently.
What you are after in a FF is how good are the tolerances and mechanics of it mostly. That will imply the amount of lag you'll be getting when your AC pulls focus on it. Besides that some offer the ability to do single and double (AB), stop marks, removable marking discs and reversed gear for non cine-standard rotation lenses like Nikons and Zeiss ZFs.
I have bought a Lanpart FF. Their top of the line one with damped mesh and reversed gear. This one also has a quick release rod clamp that allows you to pull it off or clamp it in without removing any other bits already on your rods.
With the reversing gear it will cost you roughly 500 UK Pounds and I can say that I'm very happy with it.
Edited by Alexandre de Tolan, 11 January 2014 - 11:10 AM.