Correct. The SX-1 provides the following capabilities:
IBM-PC AT keyboard port.
9-pin serial port.
Amiga standard parallel port.
Amiga standard RGB port.
Amiga standard floppy drive (use an external drive as DF0:. For more
drives, daisy chain them from the first one).
2.5" internal IDE connector (drive fits inside the SX-1).
3.5" external IDE connector.
SIMM socket for up to 8 meg additional RAM (restricted to 4 meg if
you intend to use the FMV cartridge too).
Audio input (karaoke).
Internal battery backed clock.
Pass through connector (for other devices, eg. FMV cartridge).
You are looking at $50-$150 depending on the seller. Often, they come bundled with a CD32 and a drive which puts the total price at $200-$250.
In reality, you can get away with just buying an Amiga 1200 if you plan on running games off floppy. 95% of Amiga games are on floppy anyway. Some of the later stuff came out on CD-Rom, but it's not enough to justify buying a CD-Rom drive for an Amiga 1200.