We need a RB more than we need a striker I think.
And as much as I rate A-Rod and think that he could technically cope with the switch to CB, I would prefer a faster player there.
I'd spend a bit more to get a great CB and starting central striker, over a RB. Gulley/Fenton will do better with a better ball playing CB alongside them.
A-Rod thinking would a long term project. He needs more games under his belt.