Personally, I would say go for the transfer. You need that kind of money especially when you're 5 boxing imo. Also, while the time it would take to level a paladin to level 16 would be pretty insignificant, the time you could save by boosting your shammies with the higher level pally would be pretty significant.

It really breaks down to a time vs money issue, and frankly I see the time gained by this transaction as greater then the money you put into it.