VA Takimoto Fujiko revealed in her blog that she has recently been scarce of jobs and she couldn't even participate in the auditions of the Spring-term anime. She said the producers tend to employ newface Seiyu with low guaranteed fee or popular idol Seiyu.

The guaranteed fees of Seiyu are determined by a ranking system. Each Seiyu is ranked A, B, C... according to the experience and the popularity, and the guarantee fee increases as his or her rank goes up. This system brings about a bad effect that the producers avoid to use veteran Seiyu with higher ranks.

Ref. The guarantee fee of a 30min episode anime ($1 = 100 yen)
newface: 15,000 - 20,000 yen
highest rank: 45,000 - 58,000 yen

Source: Takimoto's blog
Source: Seiyu on Wikipedia