I would make it the lowest possible because many people would buy 2 of them. If it is a set frequency it should be about $20-$30, if it has an A/B switch sell if for $40-$50, but people need to buy the set frequncy in a pair, so it will be about $40-$60 for the pair. $10-$25, as someone suggested, is a bit too low for a good RT.