Hola. Unless you already got 3.1 roms or have a way to buy them really cheap, you should consider buying an a1200. It is by far a much nicer machine, and the price for the roms can easily match the price for an a1200.
Please remember the roms will let you run aOS 3.1. But it wont give you the AA chips. 68020, IDE, possibility for faster cpu etc.