If you're already considering a guided system (GATCO, Lansky), here's an idea.
The good thing about these sharpeners is that you don't have to buy a complete set to get started. The clamps and hones can be purchased individually. If I were looking to spend no more than $50, I'd start with at least a Coarse and Medium DIAMOND hone, and a clamp (obviously). You don't even have to buy the 'sharpening oil' that is normally included with the sets. You can lubricate everything with just water (that's how I use these). The Coarse hone will be enough to allow you to reprofile & form a burr on most knives, and the Medium will then produce a decent working edge for most any cutting situation. You won't end up with a highly polished edge, but you don't necessarily need that anyway. And stropping afterwards can be done with an amazing variety of cheap and commonly available materials (there are many threads on the subject here). The guided systems, in my opinion, are very good for demonstrating the benefits of maintaining a constant angle, and in doing that, will hopefully inspire you to learn more (& practice).
And, the nice thing about the GATCO/Lansky hones (or DMT aligner types), is that you can use them freehand (without the guide & clamp) to do touch-ups, if and when you feel confident enough to give that a try.
That would give you enough to get familiar with at least ONE system, and might whet your appetite for how you'd like to spend the NEXT $50.