Honestly, the only Barber coins I find nowadays are the dimes, and even they are disappearing fast. I did find a 1899-O quarter once in a box.
I'm a fan of many Barbers at AU-58 and above. I've seen too many that are sooo worn down, so I enjoy it when I see a nice lustrous one. On the other hand, I'm not a big fan of the design. It was a pretty bland design and I'm not a big fan of Charles E. Barber. But like I said, I'd enjoy having a nice UNC Barber Quarter or Half around.
Of course it's a PRF, why did I say MS? So I guess the joke's on me now... but seriously it's a very special piece.
Here's an Internet picture of an 1899 O quarter. The obverse on the left, and the reverse on the right.
Barber coins are A-OK in my book, just a little pricey! I do have a couple dimes, no quarters and one terrible half.