We often have 12-15 people at our Valencia practices, and we use Quik Pro Buzzers http://www.quikprosystems.com/ , as do nearly all the CC teams in Florida. Our practice system only has 12 lights, and rarely are all of them working anyway, so we usually have some number of people slapping the table. On top of that, due to the configuration of our cruddy practice room, the players are at long, four-person tables in front of the desk from which I read, meaning wires run in rows where people walk, leading to numerous yanking of candles of the table because my players don't seem capable of paying attention to where they're stepping.
Anyway, I'm curious about buying a wireless system just for practice. We've looked at the Zeecraft http://www.zeecraft.com/all-in-one.html, but it's pretty expensive, while the "Affordable Buzzers" version http://www.quizgamebuzzers.com/ seems pretty lame (apparently it requires the moderator to hit the space bar to allow players to buzz in, so I guess you'd have to just do so at the beginning of every toss-up or something?).
So I was wondering if anyone has advice on these or other systems. I'm not interested in using a wireless set for tournaments, just for practices to avoid wear on our Quik Pro systems and to make set up and take down easier.