You can go to AutoZone, Napa or wherever to get either wheel bearing or get a wheel hub assembly. The assembly includes a new hub, the wheel bearing, and snap ring. You will have to remove the steering knuckle from car, have the old bearing out, then press the new bearing and hub into the steering knuckle. You can have this done at a machine shop. I called my local parts store (O'Reillys), and asked if they knew someone that did this. One place around me is a parts store & machine shop. If I buy the parts there, they will press out the old bearing, and press in the new one, and hub, for $25. If I bring in my own parts they will charge me $40. Check to see if you have a Napa dealer near you. I have one near me, but they said their labor would be somewhere around $50-60.
If you have ABS, make sure they install the bearing in with the magnetic pickup side of the bearing facing inside towards engine, I believe. (Check with someone to make sure of this). This is what I have read. I just ordered a 2008 Focus service manual for $9.90 in PDF format, so that should tell me.
I have mine to do also.
Check Rockauto.com, Partsgeek.com,Jcwhitney.com, etc.
I just swapped out both control arms, strut assemblies, on my HHR, and got all of it from Rockauto.com. Good prices and very fast shipping.