Is it me or is an Amiga not an Amiga without the sound of the floppy drive? I think it adds charm, down with WHDLoad!
Buy an A500 to start off with, they are cheap and pretty much reliable. If you end up using it a lot then upgrade to the 1200.
You still have access to over 90% of Amiga software titles out there that will work with the 500. Hardware is cheap/more accessible if you want to upgrade the 500