Hello,
Once connected to the Internet, you can view your DVR/ cameras from anywhere in the world and the number of "miles away" really no longer becomes a concern.
Your main decision will be to get either an intelligent, or non-intelligent DVR system. Provided that you go with a high-quality system, either intelligent or non-intelligent systems will provide you with clear recordings and fast internet viewing capabilities. However... a non-intelligent DVR is more for say... " oh damn, something happened... let me see who did it" type of situation. If you are looking to be more proactive about things, an intelligent DVR system is more of a "wake up... something bad may be happening that immediately requires your attention" type of system.
Cost wise, you can expect to pay about $820 ~ $1050 for a 4-camera pro-grade non-intelligent system, and about $1600 for a four-camera pro-grade PC-Witness Pro intelligent DVR system. Take a look at
http://cctvwholesalers.com/product.php?productid=16753&cat=279&page=1 .
If your company is family run, and you don't have to worry much about employees stealing from you, then you may only need a non-intelligent system. However, if you have emplyees or expensive inventory, and need to have more powerful, pro-active, than go with the PC-Witness Pro intelligent system.
Hit away with any more questions you may have... happy to help!