Crows and ravens aren't really pets - they're just birds that live with you. Adults are very shy, so you have to get them when they are young and bold. They're messy, they can be pushy, and they will steal things and hide them. It's best to just aim for a black and white African bird, its only about 900 bucks if you can find a breeder.
If you're lucky enough to raise a crow, after you release them they will typically stay around for at least a few years, at least the one that I did chose to... but it is very sad when they stop returning and you're always stuck wondering if they're alive and chose not to come back, or if they died.
Most interesting story about a pet crow was one I saw on a documentary about animal's intelligence - a woman and her pet crow are in her car, she pulls up to her gate and gets out to open it... the crow hops into the front and turns the ignition off, looking all proud about it.