Off the top of my head, overnight was more expensive in that accommodation was compulsory and started at £40-50 each way (for two people sharing), which is a similar price to taking the fast boat, and anyone who's into fast cats should probably do that at least once. When I collected my Blade, I missed the ferry on the way back so caught the cat, and overtook the boat that we missed at 40kts <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />

The other alternative is Calais or Dunkirk - I went out that way. Takes a similar amount of time overall, but with a greater choice of crossing times. Probably a similar price once you include petrol.

Paul