The good news... right now (10 Oct 16) there are a lot of sales going on at Amazon on some great LEGO sets.
-Star Wars 75059 Sandcrawler
-- Retail Price = $299.99, Amazon Discounted Price = $262.98
-Ideas 21305 Maze
-- Retail Price = $69.99, Amazon Discounted Price = $50.88
-Creator 31052 Vacation Getaways
-- Retail Price = $69.99, Amazon Discounted Price = $55.99
-CIty 60134 Fun in the Park - City People Pack
-- Retail Price = $39.99, Amazon Discounted Price = $31.99
There are a few more sets and possibly more will show up as we get closer to people buying for Christmas time.
The bad news... why should you buy straight from LEGO or LEGO Shop @ Home? If you can wait it seems that Amazon (and often Target and Walmart) will discount the set eventually. As long as you don't mind waiting a few months, it seems like the set you are looking for will be cheaper. It's not the easiest thing to do, but it could save you big time. The 4 sets listed above purchased on Amazon today versus from LEGO (like I did) would result in a savings of $78.12. The Sandcrawler is rather pricey for a LEGO set, but if you planned to get it anyways, wouldn't you want to save some on it? Hindsight is 20/20, but an extra $78.12 would be nice.
My guess is LEGO is aware of this and they are still making money through Amazon although not as much as they could be. Also, LEGO keeps some sets in their pocket that are never discounted. Modular Buildings, Collectible Minifigures, a number of the Creator Expert sets, and a few others are never discounted (I don't expect to see the Technic Porsche GT3 RS discounted). We'll see if LEGO keeps it that way or not.
So what should you do? I'm curious to hear your opinions, but my opinions are to do your best to get the best price you possibly can. Wait a while to see if you can get a set at a discount, but if it's a set you are really looking forward to, then go for it. Really it's all about how much do you value the purchase.
Happy building!