I saw it looked simple to use.
It is a very straightforward OS without all the complexities of Windows or hidden garbage going on in the background, but as for "simple"... eh, again, that depends entirely on what you want to do with it!
Either way, welcome! You can check your local craigslist, ebay, or Amibay (a moderated site for buying & selling old computers), all are good places to get your first Amiga. Amiga's have held their value pretty well over the years but usually A500's and A2000's can be found pretty reasonable here in the states, or you can try to get one of the NOS A1200's Petro T. has been selling (more info on that here in the forums). An A1200 has more current expansion options being produced for it, also opens up the option to use AGA software & games, but they can be a bit more expensive.
Good luck!