I will chime in, the A1200 is easy to get going (apart from the scandoubler, which can cost 150 EUR - if you can even find one to buy).
If you use a VGA screen (or flatscreen, since all but a few cannot take a PAL signal at all), you will not like the choppy refreshrate in games. It has to do with the 50Hz refreshrate - a very few flat screen monitors/TVs do 50Hz. If you're connecting to a VGA CRT that goes to 50Hz (many do), then it's fine, of course.
If you can stand running it on a TV that takes PAL, or a normal home computer monitor such as this
, then you could basically get away with buying a stock A1200, and spend about 40 EUR on a CF card, an adapter, and a flatcable.
The CF card runs very fast as a harddisk, and if the flatcable is 12 cm or so you could slide it between the case halves and fasten the adapter on the side of the case, so you can update the harddisk contents easily.
I have no harddisk in any of my 4 Amigas, just CF adapter slots and a single CF card which I stick in the one I turn on and use at the time.
I reckon you could get a used A1200 for 60-70 locally. If the condition is good and you can test it before buying, go for it! But otherwise you might end up 'inheriting' its problems.
Amigakit offers brand spanking new and non yellowing ones for around 180 EUR, or refurbished ones for less. If you've given up on your A500, you can use its power supply, so a refurbished one less PSU from Amigakit could fetch less shipping cost and be a good solution.
If you really want high resolution and lots of colors, you need an Indivision, an accelerator or fastram expansion, and OS3.9 or later. You can always buy that stuff later, it's rumored they will make another batch of Indivisions in a few months.