I always start with the assumption that everyone has a hobby. It doesn’t matter what it is, but it’s there. maybe you collect ceramic thimbles, perhaps you race dogs, fly model planes, follow your football team around the country: the details are unimportant (for this). Everyone has a hobby.
Everyone also has a limited amount of money to fund this hobby, once they’ve paid the bills and accounted for the boring stuff we all have to. In one sense, whether a hobby is expensive or not is really just comparing what your budget is to what you need/want to pursue it. When a gamer (someone who has this hobby) says it’s too expensive, they mean they want to buy stuff they can’t afford. When a parent says their child’s hobby is expensive it’s the same thing: cost exceeds budget. But is gaming expensive when compared to other hobbies? I don’t think so.
What do we compare it to? Well what constitutes a hobby varies depending on who you ask, but fishing generally comes out near or at the top, and I think we can agree that this fits the bill. Going out to the theatre might be a different kind of hobby we could look at.
Theatre-going is relatively simple, so I’ll look at that first. Going to a performance that lasts an evening costs quite a bit. You’ve got to get there, buy the ticket, maybe buy a programme, some refreshments, and so on. Using the local theatres as a reference point, this could come to £30 without trying hard (£20 for a ticket, £5 for travel/parking and £5 for programme and/or refreshments). I’ve deliberately erred on the side of inexpensive here, though you could, of course, cut even more corners. When you’ve finished, you have nothing left except possibly a programme for the bookshelf. So, £30 for an evening’s entertainment.
With fishing I’m on slightly shakier ground as I don’t know all the costs, but I’ve looked at some local shops so let’s make a start. You need the tackle. A rod for £100+, reel at £50+, net, chair, bait box, hooks, bait… the list is not short. I suppose a stick, some string and a bent pin are the minimum requirement, but nobody seems to struggle along with that. I used to walk along the canal to work. On a saturday morning there were often fishing competitions, with a chap every few yards. Each had a chair that made Captain Kirk’s command throne look like a wobbly stool. Not only were these grand seats comfy, they had all manner of boxes with compartments that folded out, and popped up, containing wriggly things in every colour of the rainbow. Beside them were (typically) a collection of several rods and several more nets, with a trolley to get it all back to the car. The fellow himself was invariably wearing attire that told the others he knew what he was about. I’m told that fishing also needs licenses and suchlike paid-for permissions, adding to the expense. Whilst there may be a few who make do with the bent pin on some string I mentioned earlier, it seems that most of the fishermen I’ve seen on the canal would get little change from £500 for their kit, and many have spent a great deal more. A single reel or rod can cost that much on its own.

In some ways (none of which are illustrated above) fishing seems like gaming. There is a high initial investment, and then a continual trickle of expense, but in the main you could sail along and game or fish for years with what you had. Of course, anyone who can buy new toys for themselves will generally do so, but you don’t have to.
Comparing gaming to either of these makes me think that gaming is pretty reasonable. A Dystopian War starter fleet and rule book will cost you £45, and you’ll get more than one evening’s entertainment from it and even if you don’t then you have a tangible object you could stick on Ebay and get half your money back. This makes gaming look pretty cheap compared to going to the theatre.
A new 40K army, bought from scratch, will cost a lot more. The most common army is Space Marines. Let’s say the Black Reach box and a Battleforce for about £100 (a bit more if you buy it direct, less if you raid Ebay). Then there are paints, glue and various tools, so let’s say another £50 to give you a nice little starter force. At £150 it has to be 5 evenings’ entertainment to equal theatres, and this sounds like no problem. It’ll probably be many more, even if you don’t count the modelling and painting (which you should). So even “expensive” GW games are not that pricey. How this compares to fishing depends on how much time you spend, but one day a week would be about the most an average fisherman would make at a guess, and probably not all year round. Gaming might be an evening or sometimes two a week, but it’s all year round. I would estimate a similar average of time spent between the two. Going back to the costs then, I’d say that gaming doesn’t come pout badly against fishing.
Of course, all this is fraught with generalisations, but you can see what I mean. Much as we might like to complain about the costs of this model or that game, in the end we get many hours of fun from a relatively small outlay.