I understand the gripes about cost, but really it's one of the things I don't complain about. Not that I have an endless source of income, but let's put it into perspective in a couple of ways:
First, a lot of the aftermarket parts come from smaller "Cottage" industries, or in other words, guys like you and me making parts in their garage. I exclude the "Big Guns" like Eduard, Aires, and so on, but they have their own problems to. Just as an example let's think about someone that makes vacuformed canopies. He has to pay for his vacuum form machine, he has to pay for his materials, he has to pay for his packaging, he has to pay for his time making the master mold, and he has to leave a little room in there for profit. Then, how many copies of a canopy for a particular plane by a particular kit manufacturer in a particular scale do you think he's going to sell? 100? Maybe. 1000? Unlikely. In that perspective, $10 a copy isn't a bad price.
Second, think of it like this: You spend, say, $50 on a kit, another $50 on aftermarket parts, another $30 on paint and glue. That's $130 total for a pretty in-depth kit that is going to take some time to build. If you spend 100 hours on it, which is pretty optimistic in my opinion, that is about $1.30 an hour for a fun hobby. Compare that to the cost of fishing or hunting or golf or flying or any other hobby. Building models is comparatively dirt cheap.
This hobby tends to get expensive only when people try to blow through a kit. What's the point in finishing a kit in a few days or a week only to start another one? Take your time, do the best you can, and try something new on everything you build. I spent 16 months building my last three models, and each of them really needed some more time spent on them. Enjoy what you are doing, take your time, and do your best.
Third, you don't have to buy expensive kits and a bunch of aftermarket parts. Look around at all the scratch-built things that some people build and most of us, myself included, look at in awe. Pick up some styrene sheets and rods and some wire and give it a try. Start simple and work your way up to complex. Not only will it drive the cost of your kits down you'll get a lot of enjoyment out of it.