Bit of thread resurrection from the archives, but I recently had need to hire a tux at very short notice (e.g. to hire on Saturday morning, to wear on Saturday evening).
The link above for Atelier Claire Schärer replied promptly to my e-mail, had loads of options to try on, the price was decent (or I thought so - 220 CHF for a 1 week hire) and includes post-hire cleaning.
Also flexible on return times as well.
All in all if any is looking to hire a tux (or by the look of it, a whole stack load of different fancy dress options) then I can really recommend these.