Which set is that, one of the licensed ones like the super heroes? There are many explanations as to why Lego seems expensive. In many ways Lego is not all that expensive, except in some circumstances like special sets.
First off - new molds. For the Hobbit set 'The Lonely Mountain' has Smaug the dragon has a completely new mold which is expensive to make in the first place. That set is still too high priced even considering a new mold in my opinion. The new mold, new character is part of the reason for the higher price. Then you have basic sets with new windscreens or curved parts. Then if you have a color being used for any part that previously was not made in that color - that requires extra time swapping out and cleaning the molds.
Next up, licensed themes. Those cost Lego more to make because they have to pay in some way to the company they are making their sets out of... such as Disney for any Star Wars and Marvel stuff.
Minifigures - Lego knows we love them, which is why figure packs have had less figures included compared to 80's packs, not to mention have probably had the greatest increase in price compared to sets. New figures in your Star Wars sets? They know you will still buy it, even if the price is a tad higher than normal. Again, the appeal to new minifigures is generally focused on licensed themes. A new generic castle guy? Nobody really cares. A new Green Lantern from the DC line? Everyone goes crazy.
Set design. Even the most complicated designs in the 80's and 90's were still fairly simple by todays standards. There was little to no SNOT building, and regular sets rarely used technic for more complicated architecture. One of the earliest times I remember this was Blacktron 6987, where the technic beams and gear system allowed you to open the sides up. For the most part however, major integration into designs were pretty slim compared to now. This requires a bigger team of people to figure out a design, and then to create a working prototype, all within a given price point. Making a new set from scratch, especially a complicated one that will have appeal to the masses requires a lot of work.
Quality control/Customer service. Every Lego brick ever made works with any new one. You also rarely see bad pieces and if there ever is a problem, you can get the replacement parts free by calling them up, no questions asked. Few toy companies are that good.
Lego sets have always been a little on the expensive side no matter when they were made. If anything, many sets are cheaper simply by comparing prices of older kits, parts per set and then figuring inflation into it. Also, back in the 80's and 90's, sets were much smaller. The 'big sets' like Blacktrons Messgae intercept base, were as big as you could get at about 800 pieces and 10 cents a piece. Those were the kind you had to wait until Christmas for. An 800 piece set is a moderately large set, but is still easily surpassed by what is now considered the 'big sets'. Many of those big sets like modulars, trains, or cargo ships can range from $130 to $200. Then you have UCS sets that can range well above $200. Lego also outputs so many sets and themes that unless you are super rich, you are never going to get everything that is always made.