Sorry for the late reply - neck deep in a build.....
Anyway - The DeVilbiss are considered among the best made - and not quite as costly as you might first think - here's an example of one that would be a good "starter" for someone looking to do regular spraying (regular as in at least every week):
http://www.ebay.co.uk/itm/Devilbiss...787?pt=LH_DefaultDomain_3&hash=item43d59ca173
This one requires just 5cfm's at lowest demand.
You might be wondering why I would recommend a solvent ONLY based spray gun - and the reason is that spraying water based paint, for a novice is actually pretty tricky - many factors have to be taken into consideration:
- paint viscosity is far more critical to get good atomization; too thick = spatter, too thin = massive overspray (misted paint like fog that gets EVERYWHERE)
- ambient temperature - a warmer day will affect both how the paint acts at the gun and flows out over the surface
- getting the air pressure feeding the gun right is also trickier - too much and you'll have horrible (paint) runs, too little and the paint will spatter and dry in the nozzle before even getting to the surface - or worse, flow AND spatter (think pebbledash).
- paint application technique also takes more time to master, because of the faster drying time.
There are additives like floetrol that will help, but only marginally and most of the above will still need to be considered.
I know that solvent based paints (oil mainly) take longer to dry, and require a bit more care in where you spray, but spraying solvent based is far more forgiving; ambient temps don't really affect it until you get to about 5deg, air feed pressure is also simpler because the paint is much less likely to clog the needle leading to spatter, application is simpler because of the enhanced flowout (self levelling) characteristics requiring a less practised hand.
There are ways to be able to cover both sides of an item using slower drying oil based paints - like hanging them vertically - or stacking them with painters pyramids.
If you really have no choice than to spray water based paints, then I would do several practise runs first, preferably in the area you'll be doing all your spraying (if in a semi stable workshop environment) on a similar surface to see how the paint acts - if you are going to be painting objects that require several passes per side then practise by buying a roll of fairly heavy lining wallpaper and making a frame of some kind to make a test surface, and make test passes with the normal overlap trying to get even coverage on a single pass, but be warned if you are doing it in open air outside, the weather WILL complicate matters so that a setup today won't work tomorrow if the weather is warmer by more than 5deg (and sometimes less).
A cheaper gun just to do testing and see if spraying is something you wish to pursue:
http://www.ebay.co.uk/itm/PRO-HVLP-...258?pt=LH_DefaultDomain_3&hash=item3f34337d2a
This is about as entry level as I would go price wise.
This will take water and solvent paints, the regulator will help with setting up, and not too expensive that you could buy 2 - one for oil and one just for water - I do not recommend just 1 gun for both unless you are EXTREMELY fastidious in your cleanup after (you have been warned). If you buy more expensive later this basic model can be used for priming.
Lastly - prep the paint to be used properly, mix it up well, add appropriate thinner as required, FILTER IT!!!!!! before it goes anywhere near the gun (tights are good) - even twice won't hurt.
Oh and only mix up what you need - thinned prepped paint if left for long periods can go weird when stored - never tested this, but I've read such advice on many spray webpages.
Spraying is something that does take a fair bit of practise to get consistent results, but once you know how, painting doors, furniture etc will give you excellent results time after time; and far quicker than rollers or brushing.