A quick ebay search for the hugo boss james sharp 42 in the completed listings brought up a number of them. Seems like a lot of people ask around 150 or so for used, but they really start selling/moving in the 100-80 range.
If you know your size and how a particular brand fits- ebay can be the way to go. A lot of people buy there- For kicks- there were a lot of suits selling in the 3000-4000 range and one for 12,000 that actually sold.
Who would have thunk it?
edit - the downside to selling on ebay is that you have to take the time to photograph it properly and arrange/manage the listing. There are huge internet info on photographing clothes/etc.