Passive or Powered monitors?

I wanna buy some alesis mk2 monitors. The passive joints are $199.99, while the powered joints costs $399.99. with $200 dollars I could buy a professional amp from a pawn shop. Can somebody please give me some input on these monitors cause I never dealt with them before. I tried searching the forum on this topic but couldnt find squat. All I wanna know is if its worth spending that extra $200 just for the built in amp the powered monitors bring, and if yes please explain why.

For me personally, I must use powered monitors because I'm dealing with limited space. My studio is basically a big closet, and having passive monitors would mean more space being taken up by amps and cables.

Good point. I almost feel like a complete fool for asking that question. Its all common sense. 2 bad I ordered the passive monitors before having the chance of reading your reply. I just couldnt pay 200 extra just for a built in amp at the time, cause I was thinking, what if the amp is wack or something. guess I'll be pilling up more shyt in my tiny room.