Oh, I understand now. You already bought the pair of projectors, thinking you were getting a good deal without looking forward at how you would go about blending the image to hide the seem. Since you have already spent some money, you are insistent on throwing good money after bad, when you could have just bought the right thing in the first place.
It all makes sense.
Again, if you want a huge super-wide projection, a 1080p projector running a custom resolution of 1920x720 would give you the same 2.66:1 aspect ratio that you will get with a pair of 4:3 projectors. Given the same aspect ratio, you can blow it up to cover the exact same chunk of wall. This brings with it some pretty significant advantages. You don't need any special $800 (or hidden price!) hardware/software solution to match up the seem. You get better focus and geometry in the center where your eyes spend the most time. Setup is far easier and will be certain to work for far longer. Input from non-PC components is far simpler, using common HDMI-input PC hardware. In short, everything will work better
Even if your $800 chunk of software to get these $450 projectors running well works some serious magic, that seem will still bug you every day. Can you return the projectors, or are you really locked in to this non-optimal path? $900 plus $800 is not a deal when a single $1000 projector would work better in the first place.
Warpalizer? If they don't tell you the price before you order it, that means it costs more than the $800 option that you already found.
Final thought: If a pair of 4:3 projectors with a seem down the middle was a good idea, it would be a hell of a lot more commonly implemented with solutions ready to go. Solutions are not readily available though, are they? What does that tell you?