How high are you flying, and what kind of rocket? If it's with a G motor as I suspect it may be, you'll probably be able to keep a visual on it for most of the flight. You may want to think about a "beeper", chances are that it will work fine for this kind of flight, and they're under $30. They're also very useful later on; I know people that still fly with beepers even with GPS tracking. If you're going out of sight and it's likely that you aren't going to see it again until you find it after it's on the ground, you need either a RDF tracker (point it at the rocket and it beeps if you're in the right direction and/or getting close) or a GPS tracker (which actually tells you exactly where the rocket is). Neither of those is going to quite fit into your under-$100 budget and license-free requirement; RDF trackers generally require a technician-level ham license, and GPS systems are somewhat higher. [Shameless plug... Eggtimer Rocketry GPS trackers are close to your budget, but they require assembly. You probably wouldn't be able to get it ready and tested by next weekend unless you're experienced at soldering.]
