Last month I talked with West Marine because I missed a sale where all their line (like Amsteel 7/64) was 40% off. They said they have that sale a few times a year and likely - but not for sure - it will be part of their Christmas promotion. If I understood the person correctly, starting Dec 7th, they will have a new special every week - I think up to the first of the year. And one of those specials might be deck line. If so, it's a great price for Amsteel; especially if you live close enough to just pick it up for not shipping cost.
You can check the WestMarine web site to find out. I'm sorry this isn't a "guaranteed" sale, but I figured it was better to suggest rather than wait to be sure it was on (people could miss it).