I am hoping this thread will give people an idea of what can be done in a small room, with a minimal budget, a lot of DIY, and help from people like @LTD02
My "budget" dedicated Home Theater build, done in a small 11' x 17' room which was already dry walled and finished. I was on a limited budget of around $5,000 to $6,000 including the equipment I already owned, so tearing everything out and starting from scratch was not a option. The room was almost all DIY and I performed all of work including building subwoofers, front speakers, acoustic wall panels, and acoustically transparent screen. A of lot of work went into fishing wires in and trying to make things work in a space that was already done. The only plans I had was a small drawing I did and an idea in my head, which probably was not the best way to go. I did end up having to change a few things as I went along.
The first thing I did to the room was build the stage. I got the idea for the design of the stage from a thread on the forums. When I was done I decided to cover It with leftover carpet like what was already in the room in order to save some money. Later in the build I mocked up the screen on the stage to see how things would look. I found that I did not like the shape of the stage and that the light colored carpet was reflecting to much light. I rebuilt the stage by widening the front opening, putting a round edge on the lower step and purchased black carpet then installed it. The cost of black carpet was minimal and I should of done it from the start.
Upon starting on the rest of the room there was a water main and shut off valve that was exposed on the interior wall that I needed to do something with. So I built some faux pine beams to cover the water main with and put a ball valve with key for water shut off so it would be flush with the beam. I built another set of faux beams in order to repeat the look at the other end by the stage.
Next I built wainscoting to tie the look of the beams together. I used a sheet of 3/4" oak plywood and ripped it in 5.5" strips instead of purchasing solid 1 x 4 oak lumber for this project. It saved me a considerable amount of money by doing it this way. When I built wainscot panels I laid them out in 2' widths, with 6" in-between so when I made my acoustic panels they would line up with the panels. Basically I covered the bottom portion of the wall with 1/4" oak plywood and then framed the panels out with the 5.5" strips I cut from the 3/4" plywood, finished the exposed inside edge of plywood with oak shoe, and capped the top with 1 x 2" solid oak. All of the oak for the panels as well as the trim for the room I prefinished in the garage before cutting and installing in the room.
The back of the room already had a closet which worked out good for my equipment location giving access to the rear of the equipment in the closet. I cut out a opening in the wall between the room and closet and framed it back in. Then I boxed the opening in with oak plywood leaving the back open, trimmed out both sides and built shelves. I purchased a Kreg jig for drilling shelf clip holes in the cabinet sides for multiple shelve locations. The equipment cabinet ended up being another one of the things I ended up redoing. I had originally planed on ceiling mounting the projector, but when I started looking at where it had to go I realized that I should of made the equipment cabinet taller and put the projector in with the components. So I pulled the trim off on the cabinet and cut the opening in the wall above the cabinet, and instead of tearing the cabinet out and building a taller one, I built a smaller box and installed it above the existing one and finished trimming it out again.
Next came wiring the room, installing can lights, running speaker wire and electrical wire. Like I mentioned before my room was already finished so it was a challenge getting everything in. What I figured out though was after cutting some of the can light holes out, it allowed me to gain access into the ceiling cavities to aid in running all the speaker wire and electrical wire. The holes were big enough I could actually fit my DeWalt drill up into the ceiling cavities. For my equipment closet I knew I was going to have a few amps driving my setup. I didn't want to have any issues so I went ahead and ran 12 gauge wire from a 20 amp dedicated breaker, and installed 12 commercial grade 20amp receptacles. For my speakers I used a wire by KnuKonceptz that seemed to be pretty good for the money. My surrounds and Atmos speaker were all going to be in-ceiling so it wasn't to bad getting the wire in for them. The fronts and subwoofers are behind the screen and I was able to run them through the unfinished mechanical room next to the theater room.