The cheapest way right now is to get a Raspberry Pi 2 B. That can emulate an A1200 fairly consistently right now, and the software (FS-UAE) will only get faster as it is optimised for this new device.
Obviously real hardware is best, if you have the space, but you will need quite a few adaptors if you want to run it via HDMI. Scart is still a good option for gaming though - most Amiga games were fine over this. Also you may have to spend time cleaning the case, worrying about battery leakage, worrying about 20 year old hardware and so on.
The FPGA Arcade is a good option if you want newer hardware that actually behaves just like an Amiga (rather than software emulation). The difficulty with this platform is getting it.