The aftermarket steering wheels are actually cheaper than the factory ones and look much better in my opinion.
The one I have in my 4Runner right now, it's the same design as the one posted in the link by [MENTION=28616]SSt4r[/MENTION] except it has this cool marbled finish. It was about $300 all in all if i remember right; just a factory replacement leather wrapped one for my 4th gen is about $600 and a Lexus is a bit more than that.
The other issue with the 5th gen steering wheel (assuming the splines are the same and it physically fits) is that all the connectors for the controls may not be the same and it may not look right with the steering column cover.