Ohh god.... here we go.
Anybody looking at Costco or any other BOX store system, do yourself a favor. DONT BUY IT. They are 100% crap. Unless you are paying more then $500 per camera installed, you are paying for CRAP.
You are not going to walk away with a GOOD system that is CHEAP. Not going to happen.
If you REALLY want a camera system for your house find some local companies that can SHOW you demos of their installs. And ask to see NIGHT footage. Also look for systems that offer this
1) IP Based cameras (stay away from ANALOG cameras, which have limited resolutions, IP is the way to go)
2) When getting an IP, make sure your cameras are AT LEAST 1MP and can output at least 15-20FPS (you may only record at 10FPS but you want to ensure that camera can handle higher, it'll tell you it's a better camera). Also make sure the cameras either have a special nighttime setting (low lux, VERY low lux) or have built-in IR lights that turn on automatically at dusk.
3) Make sure whoever is installing the system has a NY State Alarm License (they'll have a license #)
4) Avoid any integrator that charges you a MONTHLY fee for your system. No such thing. Unless they are hosting your data in the cloud, you should never have to pay monthly for a CCTV system
5) Make sure you have ample storage. At least a 4TB hard drive (storage is cheap)
6) Make sure whoever sets it up sets it up for MOTION. You don't want it recording 24/7 (unless you REALLY do, my own system is set on very high motion sensitivity, makes it a pain to play stuff back, but I like not missing anything)
7) Make sure that there is separate software you can install on your computer to view the cameras/play footage back (all systems let you go to the NVR itself, but you should not HAVE to)
Again, find out about the cameras and the night settings. See demos!
I can't tell you how many time I see my friends/neighbors who put a costco or simialr system in and they get crappy results. They are happy because "hey my cameras have IR" and "hey it was really cheap" or "hey it has an iPhone app" and the system is just complete garbage.
I can't give you a list of people who do this, sorry. I work in the government/education market place and our systems start at around $2,000 and go up to about $4,000 per camera installed.
My own home system (and a GOOD system) will comprise of the following
1- NVR (Network Video Recorder)
1- PoE Network Switch (this provides a network connection AND power to the camera)
1- The camera itself (I actually use cheap 3MP dome cameras from HIK Vision, with built-in IR lights. They handle up to 20FPS - They go for about $130 each on amazon, expect a reseller to charge you about $190 each)
As to how hard is it to install, that depends. How comfortable are you with terminations? How knowledgeable are you with computers and networking? Now adays, since camera systems are IP based, they sit on your network.
Basically you install the NVR, run a network cable from the NVR to your switch. Then you run a network cable from the PoE switch (your NVR can plug into the same PoE switch, you don't need a separate one) to the camera. You need to put RJ45 jacks on each end, so if you've never done that, better call a pro (it's easy enough to learn, but requires a special tool). Then you have to program IP addresses on the cameras, align the camera, adjust the color settings, then program the NVR by adding the camera to the NVR, etc..
IT can be a bit tedious for anybody. My dad is a smart guy. He knows a bit about computers, but I still have to help him with his system. He's able to run his own wires, terminate them, but he always calls me to program the NVR.
Best to call a pro. The Analog systems you find at costco come with wires/pre-terminated plugs, but again, it's crap. I took one of these out of a friends house a year ago, he's never been happier with the new IP cameras. Keeps telling me he wants to add more. But I had to help him bigtime with it.