alternative to app store?

I understand Apple wants us to upgrade to the latest and (not necessarily greatest) OS. I don't agree with how they try to force it by saying that apps in the app store require a certain OS, when a little investigation on the actual vendor's site shows that the app does NOT require the most recent OS. I was planning on switching the remaining PCs in my house except one to Macs. In all fairness, for gaming platforms, windows is a better deal, hence the one Windows system. I'm having second thoughts now when I'm finding that it's going to be almost impossible to get the apps I want to run on my non-PC systems unless I arbitrarily upgrade a system that's working fine. Does anyone know a reliable alternative to the app store? Oh, and before the fanboys start trolling, I don't want the latest OS. I've seen many bug reports, and personally know people who regret their decision to upgrade. I'm actually reconsidering my decision to go to all Macs and considering Linux instead, since I'm not held hostage by a single-source vendor for apps. Don't get me wrong, I love apple/macs, but I'm tired of the arbitrary decisions I've been seeing for the last 5 years or so.