Hello Emmerson - and welcome back!
Camping Cheques are running an offer of £115 (which includes three Camping Cheques worth £43.00 and a VIP upgrade for 2 people, each way, worth £40) - but it's limited to any sailing outward on a Sunday (any date during 2011) and return on a Friday (any date during 2011). Dogs would be £60 as normal, on top of this. However, if you do use Camping Cheques then it would save you a little over the £90 quoted if you consider just the ferry element, and if you were likely to want to upgrade to the VIP lounge (which includes priority loading and unloading, and a beverage, pastry and free newspaper, plus a guaranteed seat) then it's definitely worth it. If you're going 'long-term' then sailing days may suit - but for a two week holiday they are somewhat limiting!
If you're a member of the Caravan Club you could try with them. They were running a similar offer to Norfolk Lines - but it may also have expired.
If none of these 'work' for you then you might be best waiting until the NEC Show in February when Norfolk Lines might have another offer. The only thing is that available places may well be fewer and farther between waiting until then! Sorry you missed the £58.00 offer - we were able to take advantage of it!