I purchased the Swann unit you posted, and I couldn't be happier with it, for what I paid. 
  
The clarity of the cams is great, with excellent NV.  The only issue I have (and it may well be just me) - is connecting it securely through their web apps - though that isn't very important for my situation. 
  
The Swann's are remarked Hikvision - although I gather they have different firmware.   
  
After 6 months of use I would grade this system very high for a price/value package.  By far, the most difficult part is the cabelling back to the NVR.  Setup and tweaking was quite easy - and there is tons of help for specific questions on this forum and others - without having to call Swann for service. 
  
Good luck!