First of all congratulations on asking before buying. Wish I'd had the foresight to so that myself. As a newbie you maybe haven't decided what are of ABing you'd like to get into, t-shirts, fine art, automotive etc, or you may (like me) want to have a crack at all of them. The reason there are so many models, well I guess some are more suited to different types of ABing than others, for example the creme de la creme are specifically for super fine detail for photorealists and the like, some are large nozzled for thicker paints for fabrics etc, and some have different sized cups for bigger areas, some are siphon fed and can hold large amounts of paint for bigger areas, some are more affordable, and are basically intro brushes for those who aren't sure if they want to commit and spend a lot of money. And in truth I'm sure there are some that are just there to persuade people to part with money who have already got other models, but they are probably improved versions (mustn't be too cynical Lol)
Most people recommend buying the best brush you can afford that suits your needs. You get what you pay for with airbrushes, they make look similar, but the quality of materials and build make a huge difference. It's a big learning curve anyway, so you may as well learn with a quality tool (it will also eliminate the "is it me or the brush?" question when trying new techniques), and if for any reason (doubtful
) you decide it's not for you, a quality gun has resale value.
For an awesome all rounder, that is capable of super detail (with practice of course), and great valur for money, I would personally recommend the Iwata HP-CS. Everyone has their personal favourites, for various reasons, some prefer one particular brand over another, or prefer the wight and feel of certain brands etc. But I recommend this brush for these reasons - it is easy to clean and maintain, the self centering nozzle I find much easier, and the trigger mechanism breaks down into fewer parts and again is less fiddly to strip and put together. It has a 2inch to hairline (it can go surprisingly fine), making is a very versatile brush, it has weight to it, but is not too heavy, the trigger isn't too close to the paint cup so you don't keep hitting it (the last few points are my personal preferences), and it is a brush that grows with you, the better you get, the more you can get out of it. I am a big fan though, so am totally biased.
As money doesn't seem to be an issue, I think the brush people aspire to is the custom micron, the pros use them (although they are probably sponsered to - oops cynical again LOL) and I would love one!
Also have you tried SMDdesigns? They are in NI so, not Ireland, but Simon Murray is a good bloke, very helpful, have competetive prices, and are happy to ship. He also does courses I believe.