The answer to this is : It depends upon what you are looking for. I've found (with some help from the forum), simple $20 RF "beepers" where you find the rocket using your Baofeng radio (or a handheld scanner), and a homebuilt Yagi directional antenna. There are GPS units of course, but those get pricey, and if you don't want to build any part of the system, there's "Tile" or pet-trackers that are cheap and work with your cell-phone, but have limited range. There's also Marco-polo, but that can get expensive for what it is, but it's a complete system.
So my question to you is: What capability do you seek? Do you *need* GPS if your rockets only travel 1/2 mile downrange? Or are you flying to 25,000 feet and you need to be able to track for 9 miles or more? I ask because if your rockets are flying in a grass field, but get lost when they go beyond the trees, maybe all you need is a screamer attached to your chute. And those are $10 for 2.