A pair of nearfield monitors.
At least one dynamic mic and one condenser mic.
A mic preamp.
Those are the absolute essentials for any decent recording, aside from the recording device your friend will use to track. There are many options for recording devices, and whats best for him will largely depend on what kind of music he will record. Does he want to go through the computer or use a separate recording unit?
Although many mixers have preamps, chances are a mixer that would fit within the overall price range will not have the best preamps. If your friend is recording primarily one track at a time, then a mic preamp will be of better value.
For mixers, stay the hell away from behringer. They are cheap for a reason.
I'm not a keyboard player, so I can't help you there, sorry.
Cy