One unit that will fit all your criteria probably does not exist. Painting would require a larger unit with a large tank and works better with higher horsepower ratings. Screwing is not really done pneumatic. It might be better to get a small compressor unit to run nail and staple guns, and one of the small wagner painters for painting.
A pro will wear out the bargain brand units in no time and they are more prone to have problems. Even for occasional DIY, quality is usually cheaper in the long run. That being said, a bargain brand 2 gal compressor from Harbor Freight is probably around a hundred bucks or less. Their nailers and staplers are VERY inexpensive, but they are cheap at the same time
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This is probably the cheapest option for purchasing new equipment, but not my recommendation.
Porter Cable and Bostitch gets very high ratings and are comparable to other name brands found in the home stores. Home stores will carry a "B" grade line of tools, Like Kobalt, which will be cheaper and probably a step above Harbor Freight tools.
My recommendation would be to go with one of the small Porter Cable or Bostitch 2gal to 6 gal compressor combo kits. Bostitch has one with a 2 gal compressor and a gun that will use staples or brad nail. I have a Porter Cable that I bought many years ago that comes with a brad nailer and a 2" 16ga finish nailer. They have a kit at the same price now that also includes a stapler. These units will cost $200 to $230 or so.
Keep in mind that these small nailers and staplers are only for small jobs. You can not do framing or other heavier work with them. A framing gun will run at least $220 in a decent brand name. We have 8 different guns, not including the used one we bought that never worked right. So you can see that a full assortment of tools will be pretty expensive.
One last suggestion that might work for you. The 2 gal compressor mentioned above weighs about 40 pounds, and is considered a small unit. It is more than my wife wants to lug around, due to it's shape and awkwardness. There are these very tiny true compressors (not inflators) available. I have not used them, so can't really rate them. But here is a web site selling reconditioned Campbell Hausfeld in like new condition. They have one there that is 1 gal and only 18 pounds. It only has a .39 cfm, but should be adequate for a nailer or stapler. They are showing a price of $50. That and some Harbor Freight guns might work for you.
Air Compressors Direct
http://www.aircompressorsdirect.com/cat ... cts_id=560
Harbor Freight, compressors (use links to see other tool types)
http://search.harborfreight.com/cpisear ... &Submit=Go
Home Depot, Porter Cable, 3 gun combo $289
Do a search on - Porter Cable Three Nailer/compressor Combo Kit Model CFNBNS
(the link was too long for this forum screen)
Hope this helps
JD