I'm playing in a college band that plays mostly parties but also some bar gigs and I'm looking for the best way to amplify my keyboard for these events.

Unfortunately we don't have our own PA so everyone's sound (monitored on stage and heading out to the crowd) is basically left to themselves. I've been using a peavey kb60 that is just about dead and I need something inexpensive to replace it. But Basically its been impossible to use this one amp and meet the following 3 conditions:

1.) I can hear it in the mix
2.) the rest of the band can hear it
3.) people in the crowd can hear it

I assumed that I would just buy a better amp and wait on the PA that we'll be buying soon but since I've been reading through the archives of this forum, I've become concerned that I may have a fundamental misunderstanding of what I need in the first place.

When should you use a keyboard amp and when should you use speakers? It seems to me that for the same price of a decent amp I could buy a small stereo eq, a power amp and a decent 15" speaker. Then maybe I could run a small monitor for myself and position the speaker (or pair) more centrally for the rest of the band and audience?

Do keyboard amps add something to the sound that a PA speaker and power mixer, or PA speaker, eq and power amp couldn't?

Thanks in advance. Its always helpful to read your posts and I wouldn't be asking such a basic question unless I thought that I might be dangerously confused about something.