Why not just add an old PC to your home theater? Or even your new PC if you are like me and you have to have the latest state of the art. Then spend $50 or so and get an IR transceiver: The macro capabilities will blow up anything you could ever do with a hand held remote alone, and your existing remote(s) become more powerful than you could have ever hoped for.

If you use a PC that you already own, you will be well below the $100 limit you mention. You will be able to do much more than you could with any $400 - $800 hand held remote on market right now, and you can add all this power to the urc-300 remote you currently own.