Baby video monitors with all the latest bells and whistles cost around $200, sometimes more depending on the feature set. However, you can find solid baby monitors for $100 to $150 less than that, though you'll sacrifice on video resolution and some features. Cloud storage can add to the cost of a baby monitor in the form of an ongoing subscription, though that feature is usually optional.
I did recently downloaded Baby Monitor by Annie from Apple store and it works great! Don't really need to buy the expensive monitoring devices as with two children, I don't have much money to waste really. Of course it's for the safety of the children, so it's not really a waste, although I can easily use this app and it does everything what the big baby monitors do and even more. I've just used my old ipad as the second device placed near my LO.
You can expect to pay between $30 and $200 for a dedicated video baby monitor, with most branded units costing around $100 on average. Units that allow you to remotely reposition the camera with pan-tilt-zoom functionality are more expensive than those with a fixed view. Wi-Fi video baby monitors don't generally cost extra, because the lack of a specific parent unit balances out the costs of adding Wi-Fi functionality.