9 yr old behavior problems

My almost nine year old daughter has started having behavior problems within the last few weeks. She does well at school at relatives houses and with most of her friends(although she can be unsure of herself at times), after she gets home it's a different story. She will become angry and frustrated then scream at me & have crying outbursts. She seems to see the negative in all situations and she thinks everything is unfair. She will start fights with her younger sister and even hit her sometimes. She can't seem to control her impulses because she knows its wrong to act this way. I am looking for some remedies that may help her control her emotions and help her behavior. I have seen some remedies like 'mind soothe jr 'and 'k-ok kiddie calmer,' are they really worth the $40 per month? thank you in advance for any advice.