If you mean plugged into the remote powerline, yes almost any router can be used as a AP but you do not have to actually bridge it.
If you mean as some form of wireless extender it needs a special feature but a wireless repeater main problem is placement. You can not just put upstairs since it would get the same crappy signal your pc does and then repeat it. It would have to be placed in a good signal area and be able to transmit to the poor area....which may not be possible if the ceiling is causing the problem.
I would go the powerline route. It is much better than any other option to solve this....other than a real ethernet cable.