I own a 500 and a 1200, until recently I had several 1000's as well and I know some people locally who have 600's and 4000's.
The 1200 is probably the ideal machine to get started on. They are relatively common (as far as amiga's go anyway) and some companies like Individual Computers still make parts for them. For example, http://amigakit.leamancomputing.com/catalog/p … roducts_id=1113
With WHDLOAD and the various game and scene demo packs available for it, there is no shortage of software to run on it.
The A1200 also has a PCMCIA slot with CF card readers, wired and wireless network available for it. This is handy to get software on it via FTP or similar, but actually browsing the web is pretty futile.
Remember that Amiga floppies are not compatible with PC floppies. You can read PC floppies on an Amiga but you need software to do it. So if you bought an amiga 500 or 1000 with no floppies, you won't be able to use it as these models have no IDE or SCSI.
The big box models (2000, 3000, 4000) are not ideal for amiga beginners. They are more expensive and the Zorro cards to put in them are relatively rare. Plus, the keyboards are not compatible with PC keyboards, and even between models they had differenct connectors. eg the 1000 had an RJ11 connector, the 2000 had a 5 pin DIN connector, 3000/4000 had a PS/2 style mini-DIN connector.
For joysticks, any 9 pin Sega or Atari joystick/gamepad will work with the Amiga. You will need a 9 pin Amiga mouse. I advise against hot plugging the joysticks/mouse when the power is on as I've heard of people with dead ports from doing this.
Also remember that these machines use 15KHz analog video signal which is not compatible with VGA, EGA or CGA in the PC world. Apparently there are some modern LCD monitors that will sync down to 15KHz but I've tried a few Dell, BenQ and Acer monitors without luck. If you can find an old MultiSync style monitor these will sometimes work (again, I had an NEC Mutlisync V500 VGA CRT and it wouldn't work). Ideally you'll want a Commodore monitor.
There is a cheap/nasty GBS-8220 on ebay that supposedly scandoubles the Amiga signal into VGA but I've heard mixed results about it. Apparently it doesn't work right with PAL video modes and since Europe was a big region for Amiga games and demo writers, most Amiga software is PAL.
I run an ACA1230 accelerator in mine. I have a 4GB CF card, with ClassicWB installed on it, and the KG WHDLOAD pack. I mainly just watch scene demos on it more than play games to be honest.
Some of the best demos require an 040 or 060 accelerator which go for several hundred dollars usually.
There is also a mac emulator available for your Amiga if you have a fast enough processor (it was pretty painful on my 030).
If you are squeamish, don't prod the beach rubble.