Picked up a last year's Billabong Furnace Revolution 4/3 for half price recently, and I have to say, it's a surprisingly well made suit - super flexible and light, very warm, fits great, dries quick.
Definitely better quality than the lower end O'Neill suit I tried - that barely lasted a season. Much better fit and quality than the off-the-rack 7 till 8 I got last year (that ripped almost immediately, and wasn't all that warm). Perhaps not quite as toasty as the Xcel Drylocks I used to regularly buy for nearly $400, but damn close. And so far, seems to be holding up just as well. For the price ($105), it was a ridiculously good deal.
Note that I am in So Cal, where all the liberal pu##ies,, like myself, live. None of us have any idea what real winter water feels like...