I mustard mit I scored, for £50 on FB, a Studiomaster powered monitor / pa top.
It's literally all you need. But Stew I hear you cry, can it possibly be loud enough? Well, I gigged with it as backline in a large pub, playing with a 7 piece. So yes.
As others have said deep bass isn't helpful on stage especially if the keys are down there too. It's clear mids you'll hear.