For those who don't play a lot of flight sims, you should know that it is unfortunately standard practice to charge an arm and a leg for things like extra planes and extra scenery. For example, regular prices for extra planes in Digital Combat Simulator (basically the only ongoing commercially developed flight sim offering "study level" military aircraft) can climb as high as 80 dollars. 80 bucks for one plane. Then you pay extra for campaigns, usually around 10 bucks, which may require terrain that costs 40 bucks. There are frequent sales but you get the idea. You can check out the x-plane 11 store page on steam to get an idea of what they charge for airports, but extra planes for that game range from 20-ish to 65 dollars. The market for people who pay for flight sims is pretty tiny nowadays so developers need to make money to continue development by selling DLC at higher prices. It sucks and it gets expensive but that's how it is. Prices can really escalate if you have the need to buy all the DLC and you don't wait for sales. Whether its worth it is obviously up to you but hardcore fans shell out a lot for software and hardware (rudder pedals, hotas systems, flight yokes, button panels, head tracking/VR, etc).
So prepare yourselves, lol.