The 1905-O Barber Quarter is considered scarce overall. It does not fall in the 10 lowest mintage coins in the series but it is definitely on the lower mintage spectrum for the Barber Quarter series. Most dates for circulation strike Barber Quarters have mintages in the 4 million range more or less. Anything with a mintage over 4 million is usually considered a more common issue. And anything with a mintage closer to the 1 million range is considered much scarcer.
The 1905-O Barber Quarter is very hard to find in Uncirculated condition. Examples in MS65 and higher are very difficult to obtain in the market. And when MS65 examples or higher become available, expect to pay thousands of dollars to obtain one.