I would recommend Ari Ben, now called aviator college. I did all of my multi time building there and am instructing there now. It might not be the fastest, but it probably is the cheapest. The number of hours you fly per day depends a lot on you and your partner. The slackers won't fly after midnight and will cancel if there is a could in the sky, others will fly every night from 6pm to 6am. The airplanes are all old, but the MX is pretty good. The current director of MX has been there for about 3 years and he is great, so the stories you've heard about their MX from the past simply aren't true anymore.

I'm not sure exactly what the price is now, it was about $80/hr wet when I did it aver a year ago, fuel prices have gone up a lot since then though. Even if you don't want to count the safely pilot time, you're still logging multi time pretty cheap.

Flight Training Programs - Aviator Flight Training College