I got a new MBP last year after a ~10 year old MB Air died on me. I guess I should have updated this thread with what I ended up doing:
Replace MacBook Air battery -v- Replace Computer
It is slightly heavier, but I think the new Air would have been also. Overall, it is a great machine.
Costco and Sam's seem to regularly have these on sale; if not right now, wait a week or so and check back, unless you need it ASAP.