Brush, Spray or Airbrush?

As I try to find an opportunity to actually finish the final touches (mainly varnish) my first models for many years and resume work on the Dakota I have been musing which approach will suit my needs best for future painting projects.  My brush work on these first two projects has been pretty poor if we're honest about it (but lessons were learnt) and with the prospect of the much larger surface areas of the dak awaiting me I wondered if getting an airbrush would/might be the solution. 

I haven't done a great deal of reading up on them so far, but what I have read makes me wonder if I would actually benefit or if the thinning down and cleaning would mean the novelty value would wear off pretty quickly and it would end up clogged up and abandoned in a drawer.  Then there is the cost... You can pick up the actual airbrushes quite reasonably, but are the cheaper ones actually any good, but then there is the compressor and other paraphernalia to consider.  I have got a birthday coming up which might cover all this though.

The other option which occurred was to use the hobby aimed aerosol cans from the likes of Humbrol and Tamiya and others.  Now these aren't hugely expensive individually, but I'm sure the cost would soon mount up when you need 2 or 3 colours plus primer and then varnish.  Coupled with the fact not all colours are available (well in Humbrol at least, I haven't investigated Tamiya in that much detail).

On the other hand I could just carry on as I am and stick with a good old fashioned brush job (perhaps with cans of primer and varnish).

So any experiences or advise you might have would be gratefully received, I've seen some amazing work from many of you so would value your opinions.

Cheers
Andy