I am aiming for professional movie quality sound.
Then you hire professionals who specialize in production sound and audio post.
First, just because your shoot takes place in one room doesn't give you any sort of an edge. It is probably a lot less quiet than you think, and I would give long odds that the room is highly ambient (meaning it is very reverberant). So you need plenty of carpeting on the floor, and lots & lots of sound blankets just out of the shot. Make sure that all of the electronic appliances are unplugged - no, turned off is not good enough - and that the batteries are removed from the cellphones, PDAs, etc. of everyone on the set and nearby.
(BTW, who is going to be swinging the boom-pole and recording & monitoring the production sound? That's the person who really needs to read all of this!!!)
You get the mic in as close as you possibly can pointed at the notch at the base of the throat/top of the breast-bone. It needs to be moved from actor to actor as they speak their lines - without getting in the frame and without casting shadows.
http://www.thompsound.com/old-site/Articles/QSFT/zen_boom.pdf
After you have synced the production sound to the visuals and completed the edit it is time for audio post production. If you truly want professional level sound you will delete all of the sound between the lines of dialog and replace it with room-tone or ambience. Then you do a complete Foley, which is replacing all of the human made sounds (footsteps, props handling, clothing, etc.) and complete sound effects (vehicles, doors, other props, ambient sounds, etc.) You then spot the score & the source music, then mix everything together in a certified mix facility.
As can't afford a professional audio post and you are on a budget everything is going to hang on the production sound. You most probably won't be able to do a complete Foley and probably only minimal sound effects. Your mix will be rudimentary because you won't have decent speakers or an isolated, treated room.
Start with spending some time at FilmSound.org. The read "The Production Sound Bible" by Rik Viers and "The Practical Art of Motion Picture Sound" by David Yewdall. After reading those you will at least know what questions to ask. Oh, you can also read my blog. I haven't updated it in very long time, but the basics still apply:
http://www.myspace.com/alcoveaudio/blog
Here are the basics of production sound gear at the $2,500+ level:
http://www.bhphotovideo.com/c/produc...icrophone.html - $1,000
http://www.bhphotovideo.com/c/produc...Stereo_CF.html - $850
http://www.bhphotovideo.com/c/produc...icrophone.html - $500
http://www.bhphotovideo.com/c/produc...indshield.html - $300
Sennheiser HD 280 or Sony MDR-7506 headphones - $100
Add in cables, etc. and you're at about $2,750. Later you'll add a good mixer, and then wireless lavs.
If you want a micro-budget kit:
http://www.bhphotovideo.com/c/produc...Condenser.html - $600
http://www.bhphotovideo.com/c/produc...le_Linear.html - $300
http://www.bhphotovideo.com/c/search...rch=yes&sts=ta - $150
Sennheiser HD 280 or Sony MDR-7506 headphones - $100
Add in cables, etc. and you're at about $1,500. You can downgrade to the DR-40 ($180) and save about $120.
If you want to go ultra-mini-micro budget:
http://www.bhphotovideo.com/c/produc...oming_Kit.html - $170
http://www.bhphotovideo.com/c/produc...tal_Audio.html - $120
Sennheiser HD 280 or Sony MDR-7506 headphones - $100
