As long as the Vibe looks clean and appears to be in good shape, I say go for it! We have 2 2009 Vibe GTs and neither of ours is consuming oil so far (build dates of 10.29.08 & 11.17.08). We haven't had any issues with ours in the 5+ years and 50,000+ miles we've had them. Great little vehicles for sure. We get tons of compliments on them, how they look, etc. Sporty and practical, can't beat that!
Definitely let us know if you do end up getting the Vibe and if you do, be sure and post some pictures when you get a chance
!
EDIT
Forgot to mention this... have the dealer run the VIN and see whether all the recalls (accelerator pedal and window swtich) have been done. If they haven't, have the dealer do them for you or get them done if it's not a GM dealer that has the Vibe.