How about a cockatiel? I think the male ones are the best mimics, we have one, but unfortunately we haven't spent as much time "educating" him as we'd hoped for. It does take a huge amount of time and dedication. Cockatiels are willing listeners, and with patience enjoy human interaction. Our Robbie is always pleased to see us in the morning and despite our poor teaching skills he says "hello Robbie" does great telephone and dog impressions, and a mean rendition of "Bridge over the River Kwai" !
Cockatiels are relatively inexpensive compared to parrots, and I believe they live to about 25years
Hope that helps!