It's not stealing, but you're still ripping off the developers. They're not getting paid.
Seriously guys, the apps are $10. I can see pirating Photoshop or something, you're not making any money off of it, the guys at Adobe are still getting the same salary, and you couldn't afford it anyway. But pirating a $10 app from an indie developer? That's just lame.
It's only a joke jeez. If you're really against piracy, then stick by your stance and purchase everything legally. Don't go by lame principles like, "Adobe makes craploads of money, I'm not making a big difference if I pirate it." That's like saying "Im a vegetarian but I'll only eat chicken because there's just soo many chickens in this world, and their lives aren't as important as a cows."
If Apollo was to be released in the App Store hell yea I'll go buy it, but lame-o apps like Labyrinth which used to be completely free in installer.app but now charge a price is ridiculous. Yea I don't blame the devs for seeking a bit of profit, but lame apps like iBeer, iMilk, Fingerscan etc are just ripping off money from clueless users. Also, you make it sound like the devs make their living and feed their families through the App Store, I'm sure most have proper full-time jobs.
I've bought a few apps already and they're the only ones that I've actually
really wanted and probably the only ones I will play regularly. There's just some apps I will buy and some that I won't, and I'll stick by my stance try before you buy.

All this comes down to your own principles and morals anyways. If you feel like you're doing the right thing, then do it, you can only preach so much before you turn into a missionary.