Take a look at the Princeton Tec "EOS" (Bike-version) It is a nice little light, but has a very tight beam with little side spill. The package includes both helmet mounts and handle bar mounts. I recommend using the helmet mount. The ability to pan left-right, and up-down makes up for the lack of side spill. In addition it will leave you hands free if you need to stop to fix a flat or something else. Later, when you can afford a second light the Eos will only compliment a good handle bar mounted system.
They usually sell for around 30 to 35 USD. Sorry I couldn't stay within your 25.00 budget.
Last winter my Dinotte batteries unexpectedly died on me. The Eos was my only light and I rode home 12 miles. I later purchased a Fenix L2D (cree version) that now serves as my back up light and as my primary on my folding travel bike... But I still use the Eos no matter which light system I use or what bike I ride.
It's funny you mention the Ryobi ... last year I was riding the local bike path and encountered an older gentleman on a hybrid. he was using a black-n-decker shop light. He had fashioned a box that had four sides and a bottom, but no top. One of the sides was about 3 inches shorter than the other three. He mounted it to his handlebars with U-bolts with the short side facing forward. All he had to do was take the light and set in down in the box. It was only held in by it's own weight. The shortened side allowed the "bent" neck to stick out. Very clever... Heavy, but Clever. Proof that you can make anything into a bike light.