I have bearing Buddies but they aren't a cure all, you have to be careful using your grease gun not to over pump them up.
Start bumping till you see the grease fitting start to move and STOP. You can blow out your rear seal.
As for buying bearings, there is a lot of different sizes. You must know your size.
Jack your wheel up and give it a spin, if you hear a sound its time to change because it's going to let you down.
Nothing any worse than driving in bad snowy weather and your wheel bearing blows.
Princess Auto has some but you must know your size.
Some will spend the extra money and buy the whole wheel hub assembly, keep it wrapped in you trunk.
Other thing, make sure you have a jack and tools to make the change on the side of the road. Idea do a drill: try doing in your driveway.
I should talk, I don't have a spare, my bad.
This is the place I bought my last bearings at.
Canadian Bearing
400 PARKDALE AVE. N., UNIT 1C
Hamilton, ON
L8H 5Y2
T (905) 547-2351