1 - Stereo was not mentioned. If that is a requirement, he can move towards budget home computer speakers, still in the same $ area.
2 - don’t let the size of the Roland Cubes fool you, buskers using them are easily heard clearly from several hundred feet away, more than adequate for a home hobbyist. Their sound is proven excellent for their size and people on this board use them without issues. When I tested them out at a local Roland dealer, I was pleasantly surprised. No, not as loud or bass heavy as a Mackie Thump with a 1000 watt amp, but that is not the Aim in this case.
3 - in a hobbyist/pleasure environment, 2.4 GHz or 5Ghz makes absolutely zero functional difference, they both have the capacity to work perfectly in a 5-10 meter range.
In this scenario with a tight budget, one can still be wireless in mono or stereo for well under the 500. This is not rocket science, really, and offering advice here is not wrong. Also what shop would even think of suggesting computer speakers for someone that wanted a stereo setup (yet my own speaker set cost me $100Cdn and pushes 150 watts and has been annoyingly loud in my home many times… lol
If you start talking mixers, dual external powered speakers, wireless transmitters, you can easily go above the budget AND the complexity required for someone that all they want is to play in their living room.
I have nothing against going to a shop and seeing what they offer… but they are not the only source of knowledge around.