Maybe oversized for three cams, but well prepared for future constellations
There are also the NVR4xxx models. They are also available with PoE. Depends on your needs. If you guess one HDD is enough you could go with a NVR41xx-4KS2. But of course you'll have to look for yourself which one fits best for you. I would always recommend the -4KS2 models because of their capability for H.265 and 4K support if needed.
1HDD Models with PoE
NVR4104-P-4KS2: 4 channel, 4 PoE
NVR4108-P-4KS2: 8 channel, 4 PoE
NVR4108-8P-4KS2: 8 channel, 8 PoE
NVR4116-8P-4KS2: 16 channel, 8 PoE
2HDD models with PoE
NVR42xx
NVR52xx etc.
I don't want to list every model. As you can see you, the naming of the model gives your every info needed for initial choice, then you can look after the details.
NVR4xxx number is type of class, 6,7 are Ultra, 5 Pro, 4,2 are Lite
NVRx1xx number is amount of HDD
NVRxx16 number is amount of channels
-P is four port of PoE, -8P is eight ports of PoE and -16P is sixteen ports of PoE