Despite the fact that this has resolved itself in the traditional manner (http://dilbert.com/strip/1997-11-06), here is my 2 cents...
Rather than a traditional extender, you could set your wifi device as a bridge. If you still need wifi in the apartment, hang another AP from that. In my experience, this eases some of the issues related to trying to use an extender at extreme range. If you have access to an ethernet port on the source side, you can use a pair of directional devices for the bridge (like the Ubiquiti NanoStation line) to extend range to many times the traditional max. At my last job, I successfully used a pair of nanostations to bridge a gap of nearly a mile (with rough, but not clean line of sight).