You don't need a compressor with the HVLP turbine setup and it will only set you back about $550-650 with a decent gun and just about everything you need.
It is possible to turn your garage into a spraybooth but it will take lots of work on your part. You will need to have windows on the opposite wall of your garage door for it to work properly. If not, then buy yourself a sawzall and don't tell the wife.
You will need a bunch of flat furnace filters, Huge roll of plastic sheet material, 4 squirrel cage fans, (square window fans work well but they can produce sparks. Don't say I didn't warn ya!) and lots of fluorescent lighting.
1. Clean the garage from top to bottom. Dust everything and wash everything untill it passes the white glove treatment or looks as clean as RedCarGuys garage. When you are satisfied with how clean it is, wipe everything down again.
2. Cover all three walls and ceiling with plastic sheets using bricks to weigh down the bottom of the plastic to the floor and stapling the sheets to ceiling. Cut out around lights and duct tape plastic to light housings.
3. Mount two fans in window positioned to bring air into the garage. Tape filter material onto outside of fans. Cut plastic around fans and duct tape to them.
4. This is the point at which you should bring the car in to be sprayed. I would recommend you get some tripod fluorescent light fixtures to avoid shadows. Be sure the car is ready to be painted at this point!! Remove all masking paper and wipe entire car down with tack rag. You should also wet down driveway and garage floor to keep the dust down at this point. Bring car into garage and seal door with plastic sheeting leaving the door open just high enough to clear the remaining fans. Place these fans on floor so they will draw the garage air out of the garage. Cut and seal these fans and put filters on the garage side of the fan.
5. Be sure to cut an exit "door" for your self to get in and out of the garage between coats etc. Now you should mask off the car a final time with masking paper/plastic. You should be ready to spray at this point. But be sure to have adequate breathing aperatus as the chemicals in paint are very toxic. Also try to route all power cables outside of your spray booth when possible. The fumes from paint are also very flammable. Try to imagine that you will be painting with gasoline before you start looking for spark hazards.
I am sure that I forgot a few things in here, but this is basically how I've seen home paint booths set up. You probably should not be doing this at your house and your local bylaw dept. and insurance company would probably blow a circuit if they found out you were painting cars at home, so be careful. :xyxthumbs