What would be a fair price increase?

[tigwig]

I have been a childminder now for nearly a year. I am full and expecting my 2nd child in Dec/Jan for which I am only planning to take 2 weeks maternity leave.
From Feb 2010 I want to increase my prices as I am charging much less than anyone else is. Unfortunately I did charge the going rate of �3.50 per hour but reduced my fees after wrongly thinking this was why I wasn't full. I am fully qualified and have more than 12 yrs experience and a glowing Ofsted result so there is no reason why I should be so cheap! I currently charge �130 for a full time weekly place when others are charging at least �150. I can't suddenly up my price my �20 a week but would �10 a week be too much? I would appreciate parents opinions especially those who pay for childcare. Another thing is local nurseries charge loads more so parents wouldn't exactly be able to say they would go elsewhere as it would cost them even more. I need to charge more but don't want to upset the parents! Please help!