First of all, while it is true that many mainstream comic books currently being produced are not aimed at young children, there are plenty that are.
For example, Sequential Tart mentions the recent Thor series by Roger Langridge (words) and Chris Samnee (art). This was a title that I initially bought for myself and wound up passing on to my son. This was a true all-ages book; it wasn’t for little kids and didn’t have anything you would feel uncomfortable having your child read.
This particular Thor series didn’t last very long, and was not part of the regular Thor continuity. (Note to those who don’t care about comics that much: “continuity” in comic books refers to the ongoing storyline of a character or collection of characters. It’s important stuff to most people who read comics.) Even regular readers would be forgiven if they didn’t notice this series amongst the slew of other Thor books that came out before, during and after the Thor film.
Sequential Tart (I really like that name) also brings up Tiny Titans, which my son and I both like a lot, although lately I think they may be running out of ideas. Tiny Titans is a funny and strange book. It’s clearly aimed at young children, but has numerous references to classic DC characters and continuity, particularly from Teen Titans. For example, Slade, aka Deathstroke, is the Principal of Sidekick Elementary, where all the Tiny Titans go to school. That’s kindasortafunny if you know that Slade is the Teen Titans arch-villain. If you don’t know that little detail, it doesn’t really matter. There isn’t any deep storytelling in Tiny Titans, but it’s usually amusing enough to be worth reading.
A bigger issue is the price of new comic books. Most comics aimed specifically at kids cost $2.99 per issue. This means that most kids are probably not doing what I did, which is take my allowance to the corner candy store to pick up the latest issue of Spider-Man. In my case, I buy comics every week for myself and my older son, something that I doubt very many parents are doing. When my kids are older, assuming there are still comic book stores to go to, they may or may not decide to continue buying comics on their own.
One way to avoid this is to buy trade paperbacks; both of the links above are for paperback collections of the comics mentioned. Trade paperbacks are generally less expensive than buying each book individually when it comes out. They also look nicer on a bookshelf. You can also get them at your local library for free. Free is good.
Used copies of trade paperbacks / collected editions are also a good way to save money. Midtown Comics has an in-store sale rack where I’ve found a lot of great deals. They also have sale items online, although I personally prefer to shop in person when I’m just browsing and don’t know exactly what I’m looking for.
You can also read Fart Cop on DaddyTips for free. In case you forgot.
For more kid-friendly comic book suggestions, check out this Sequential Tart article.