[n00b on demand]

as i was driving today i noticed something i never heard before in my entire life......ive been told that when ur bearings go bad there is a loud roar that gets progressivley louder as they get worse.....i took the car out this morning and had no problems...car ran like usual....usual sqealing from the brakes cuz i need new pads.....but as i was accelerating i hear this loud shreiking noise coming from the back of the car...primarily from the rear left.....it would last for a second and then go away....mostly happened when traveling uphill......im praying to God that it isnt the wheel bearings and that it is something else because i really dont have the money to pay for new bearings.....the noise sounds like the same squealing from my brakes but the noise occurs when i accelerate.....its really weird...this is the first time i am ever hearing this too....im not gonna take the car out again...next stop is to the mechanic...but i have no clue whats wrong and am praying its not the bearings......if it is the bearings how much does it cost to replace them?...and can any mechanic do it or should i take it to Subaru?....and would Subaru charge more?.....i need help ASAP