I would not buy a used airbrush and I would not go for an airbrush sold at Harbor Freight unless there are parts that are readily available for it. The needles and tips in an airbrush are easily damaged and if you do damage them and have no way of replacing them, then the airbrush is useless. A compressor from harbor freight or Walmart or any other place will be fine but I would get a name brand airbrush. Some beginners like an Aztec because it is light and easy to clean since the atomization of the paint does not happen in the airbrush body. Iwatas are great. Real workhorses. Badger is making some nice Renegades these days. Another thing to consider is the type of airbrush. General purpose ones that will do a wide spray pattern or illustration brushes that will be able to paint a hairline. Also, some brushes can use different needles and tips to do different spray patterns so it will be a more versatile tool. Along withe an airbrush, hose, compressor you might want to consider getting some good cleaner to THROUGHLY cleanout the brush and possibly a water seperator to keep water out of the line and messing up the spray pattern. I like compressors with a large enough air tank with a pressure switch on it that way I can work off the air in the tank, (silent) and then when that starts to run out the comp. kicks in and refills the tank. An airbrush really needs to be maintained well. if you let too much paint build up and dry in the body it will be a pain to get it out. That is where the really good cleaner comes in. Water based paints are not as durable as laquer or enamel paints, but are much easier to work with. I also found that a dual action airbrush, though harder to get used to at first gives you much more control in the long run. Dual action means that you push down on the trigger to get an airflow, and then when you pull the same trigger to draw the needle through the tip, it gives a release of paint. More push on the trigger, more air. Longer draw on the pull, more paint. It is kind of tough to give about 20 years of experience in just one paragraph but feel free to pm me with any questions or if you want anything explained a little more.