I'd like to begin by saying that most, if not all, of the OP's points were completely and totally valid. Yes, the prices are going crazy. Yes, GW are screwing over their customers. Yes, they change the rules all the time and they release new models just to make more money and blah blah blah...
However, as one keen-eyed commenter already pointed out, hobbies, sports, interests in general will always require you to pay through the nose to maintain them. Golf was the example given by wingazzwarlord, but there are numerous others.
For example: I take a shine to trading card games as well as 40k, and if you want to play at all competitively in TCG's you'll have to get used to the fact that the rules, the cards available, and the prices of those cards all change very regularly. In Magic: The Gathering (which I don't play, personally), they release a load of cards around autumn and say "Have at it!". If you like to play Standard format (possibly the most popular), you then have 12 months to collect all the cards you want/need, build the best deck you can (which, if you're ultra-competitive, could cost hundreds of pounds quite easily off the secondary market), and play the game. After those 12 months, all of those cards are then no longer Standard legal (meaning you can't use them), and the process repeats. Yet Magic: The Gathering remains one of the most popular trading card games ever.
Another example: Let's say you're an engine-head and you want to "soup-up" your new car. You want the best stereo you can get, you want to change the paint job, you want decals, you want neon lighting under the sides NFS-style, you want fancy rims, you want big tires... the list goes on. You think any of that would be cheap? Hell no. Cars are expensive. And if you should so happen to accidentally damage your car on the roads, you'll have to spend a buttload more cash just to fix it, never mind redo the work. But people still do it. Lots of people.
Now, there are those fledgling games people have mentioned in this thread (of which I am unfamiliar, for the most part) which are apparently affordable, balanced, and fun. To that, I have but two words: "For now." My advice is not to expect that if these companies get to GW's size they will continue to price things so cheaply, or make rules that benefit the customer's wishes. A quick glance at the major corporations behind the production of goods for other interests will show you that GW's business practices are not that out of the ordinary. GW raise prices and change rules sets to benefit their monetary gains, but so do plenty of other companies.
So you have some options. One is to switch to a "cheap" "hobby", i.e., one which has rules that aren't governed by a corporation. Chess is an example, as all you really need to play chess is a chess set and a person to play with. Keep finding people to play with and your problem is solved... except that chess is very, very different to 40k, or any other tabletop wargame, in that (i) there are no miniatures to collect and paint, and (ii) with a game like 40k you can tailor and build your list to be the best based on the current rules and metagame, whereas in chess both players have the same armies and it's entirely down to the decisions of you and your opponent - no dice involved here, folks!
Another option is to continually leap from bandwagon to bandwagon on what the cheapest mini-producing company is. This might be viable, except you might leap onto a bandwagon soon-to-crash. That probably wouldn't be an enjoyable experience.
In the end, it's up to you. These are just my two cents, and to an extent my counterarguments to all those saying GW need a stern talking to about their prices and their rules sets.