basspig's 154" Seymour cost less than $1k I'm pretty sure. Sure, it's a scope screen, but STILL. It is a DO IT YOURSELF fabric. He will save THOUSANDS.
Dude, the RP setups you've linked seem to look way too tiny for this application.
When I think THIS big with RP, I think of Stewart Starglas 60/100. At $300 a sq ft, we are talking $25,000 for the glass in this install, and that's before taxes.
I think some of us still like the JTR stuff for just a bit more. How about the Triple 8s that Midnight uses both professionally and in home? Here's a linky. Perhaps you might land a discount with a bulk order, I don't know. Then again, maybe those are good JBLs, I don't know . . .
http://jtrspeakers.com/install/triple-8/
Regarding the Seymour stuff, I would email/call them for tips or warnings. Stuff like, how big can it be, how big can it be without seams, are the seams easily visible, is there a max angle of incidence of projector light that should be avoided, etc.
Linky to the CenterStage XD:
http://www.seymourav.com/screensDIY.asp
So, you say 12k budget?
$4000 for the PJ that BMX recommends.
$3600 for the front three speakers worst case scenario.
Subwoofer(s), build a Bill Fitzmaurice designed Tuba HT subwoofer, for say $300-500. Someone decent with wood can do it in a day. It is very large, I think like 3'x3'x2', but you get insane efficiency of output, with high SQ, on a very small budget! $15 for the plans. Here is one build:
http://forums.audioholics.com/forums/showthread.php?t=60906
Let's see, so . . . maybe . . . $800-1500 for receiver/processor, let's say $1300 . . . .
Pro amps to run speakers and sub . . . . (are you looking at 7.1, I don't remember), well, Midnight can give you a better idea here. Let's pretend $1500 for all channels and sub.
PJ mount ($250), HDMI cabling ($50-200), hmmmm
running total = about $11k.
Add screen cost, other speakers. . . hmm yeah budget limit about to get hit. But, for something like this, do it right! You will have an incredible theater.
Another thing to consider for screen, is Dalite High Power. I know for a fact that 159" manual is WELL under $1k as shipped. You might then be advised to rip the fabric out, and DIY frame it, but it won't be easy, and the fact that the material is as stiff as it gets doesn't help. However, this stuff has its own set of idiosyncracies/compromises . . . This stuff can come at least 159" without any seams at all, but I don't know about past that . . .
http://www.avsforum.com/avs-vb/showthread.php?t=773065