Jordan, The lack of bass in a speaker used for monitoring in a recording situation will only mean the bass is exagerated when played on other systems. Will wreak havoc on a bass heavy recording but maybe not so much on the style your friend is considering.
If your friend does decide to get monitors the KRK Rockits area a great choice, one I would choose over the Behringers. They are powered or passive as well and the 6 inchers repoduce great bass for their size and are pretty reasonable.
Rockit RP6Passive ST6 RP-6 Review You also mentioned something halfway decent. Both the Truths and the Rockit RP-6's are way more than half way decent and you can't go wrong with either one. My 5 inch Events rock the whole house and they are yesterday's technology.
