Your dimensions are off. What are the dimension of your kitchen and foyer including ceiling heights? Your volume needs to include the other rooms. My great room is about 30x15x10. However, it also opens to my kitchen, dining room, foyer and another hallway for about 10k cubic ft.
You ask this BTW after all the Black Friday sales have passed.
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Fully built cabinets, drivers and amps will eat you alive with shipping costs from online merchants. (I know from very recent experience.)
Occasionally, one can score an AV123 MFW-15 for less than $500 on E-bay or Audiogon. (assuming you aren't one of those people that insists on everything new) Other possibilities (used) are the Dayton Titanic MK III kit/assemblies,
You might still need to DIY for any serious bass. I'm thinking a couple of tubes with 12-15" (Infinity, Dayton, JBL, eD) drivers with a Europower or Audiosource AMP for now with an EQ added later. (You won't get a Maelstrom within your budget.) If you want to go the box instead of the tube route, you can opt for a plate amp from eD or Dayton/Parts Express.
BTW, one thing to opt for is patience when you have a limited budget. #1, you don't have to purchase everything at once. #2, you can definitely shop around and be patient for deals. If you get outbid on E-bay or Audiogon this week, you might win something within your budget next week!