Room dimensions and photos would help. Just saying 3,000 cubic feet for instance can translate into a 8 foot by 10 foot by 38 foot space or an acoustically nicer 9 foot by 15 foot by 22 foot space. Furnishings and finishes make a difference too. Do you have domestic limitations (family, pets, neighbors, aesthetics)? Pets can knock over and scratch nice speakers. Heavy speakers don't move easily for family/party functions. Blocking a million dollar view with big speakers is another no-no. A wall of windows or masonry walls aren't the best thing for sound either. What layout for speakers/listener(s) do you have in mind?
Why dual 18 inch subwoofers for this space (seems like overkill and a lease breaker). Is the space open to other spaces? How loud do you listen? Are you a bass head? What are you favorite genres of movies and music?
With no budget, I'd recommend the absolute killer ATC SCM45A at $6500 USD each. They are professional active 3-way designs; 42-25,000 Hz; 112 dB max output; 14 inches high, 24 inches wide, and 15 inches deep; drivers built in-house; designed for clarity, accuracy, coherency, and superior horizontal/vertical spread in a mid-field setting; used by the finest studios in the world. (Apologies the stepping on the Salk Circle, but just giving perspective.)