Money no limit:
Sony VPL-XW7000ES projector - $27,998
Elite screens motorized drop down 180" - $1,457
Egglestonworks Ivy speakers (stereo only) - $166,995
Boulder 3050 mono amps (2) - $205,000
Mark Levinson stereo pre-amp - $11,000
Kaleidacaspe digital movie player - $32,985
Budget a few thousand for cables.
Budget:
Check out Amazon and get a projector with speakers and a pull down screen for probably less than $200. Almost all of them have a USB port and will natively play movies from it.
You can go from a couple hundred to 1/2 mil and probably higher. When people say "money is no object" they don't realize that some of this pricey stuff actually exists.
What you need to do it clearly define your goals and the limitations of the space.
How big of a screen do you want? Is there total light control in the room? Because a $50 projector on a 200" screen in a bright room will not work.
Once the screen is picked out - How bright do you want the picture? Where will you mount the projector? That determines what type of projector and lens it will have.
Sound - How big is the space? Do you want to feel the action movies?
I'm using a Benq GP-500 projector on a 134" screen I built myself. I built my speakers and subs myself. I'm powering them with Crown XLS and Behringer EP series pro audio amps. Not because I want it loud (I do) but because I want clear sound. If you push the amp to the limit to get the volume you need, then the extra loud stuff like explosions don't sound clear. I'm using dual 15" subs and will probably add four more. If I can build and sneak in a refrigerator sized box, then I'll also run my 21" sub.
This is has been my primary hobby for 25 years.