I'm just going to assume that buying your own plane is not an option for you. I went to Ari-Ben Aviator a little over a year ago to build muti time. Here is my experience with them:
We called and signed up for their time building program in July 2004. My friend and I drove down there in August in good spirits looking forward to some quality flying. When we arrived they had no record of us calling and did not have us on the schedule at all.
Ari is the son of the owner and he lied to us about everything on the phone. He told us we'd be on the schedule right away just to get our money. We waited in for an entire week before we even got our first flight. Luckily we had a friend to stay with or that would have cost us about $500 extra in hotel costs.
When we finally did get flying, we did a 5 hour checkout with an instructor which they state right on their website costs $300. They charged us almost $800 each for it. Then they gave us some aircraft manuals and never told us they were charging us for them. They tried to sneak them onto our account for an additional $42 each. We forced them to refund one set of manuals since we could share them.
Once we started flying, we really did get it done fast (about 6-8 hours per night). We were only allowed to fly at night and they will only let you refuel at their base unless you want to pay for fuel yourself. That meant we could not go more than 2.5 hours away otherwise we'd have to pay for fuel ourselves.
Also their airplanes are so poorly maintained that any FAA inspector would have found them un-airworthy. They all had INOP oil temp and oil press gauges. Some had INOP carb heat. Only one of them had a working Wx radar installed like it says on their website and that one was reserved for checkrides. Their airplanes were so illegal to fly that I was scared I might get ramp checked every time. Looking back, I should not have flown them but I guess I was naive and believed the lies they told us.
Once they get you flying, you will get it done quickly. If you don't mind flying poorly maintained aircraft that are probably not airworthy, then you can get a good price on multi-engine time. Whatever you do, don't go to a "pay for training" airline unless you want to be blacklisted in the industry.