Hihi!
In my personal expierence with streaming and editing videos a good computer that's less than $600 would be the iBuyPower AM460FX, it has AMD FX-4300 quad-core 3.8GHz processor, 8GB RAM and a 1TB HDD. But I don't know how much those go for now. If it's too expensive I would get the Acer Aspire ATC-280-UR11, it has the AMD A-Series quad-core A10-7800 3.5GHz processor with TurboCore 2.0 technology that can boost the processor up to 3.9GHz for extra speed. Throw in 12GB of RAM, a 2TB hard drive and an integrated AMD Radeon R7 graphics card!
I hope I helped!
-Jailbaitasmr