Well, I wrote a short review on the F90 shuttles long time ago (only available in Chinese) http://www.ablueday.com/archives/66 In short, the F90 feather is thinner but more uniform than AS50. Its durability is just so-so(lower than AS50 if not at par), but with very precise flight. It's not built for club plays but really for tour only. If you use it often you will be broke in no time
Well, from Shuttle house, which is about the only place you can buy F-90, a tube is 4600 Yen. This is about $63.93 Canadian or $51.47 USA.
Hello Sir, I have noted your words about YY 50 - I am actually developing a new top goose no. 1 grade - interested to hear more ? sincerely Lars