30 cameras might be a bit much.
Maybe suggest an alternative...
Example:
Where we are moving to there are 4 entrances to the area. At each of those intersections there are live feed cameras monitoring the entry/exit/both ways. This is then monitored off site by a security company that also services most residents in the area. Security and residents association(for cameras) are R449 per month combined. Security company has dedicated vehicle in area that residents can contact either through control room or directly. Example given to me if a woman returns late at night she can request can meets her at home. 10min minimum required. The gaurd will then see she enters her property safely before he continues patrol. Etc, etc, etc.
That is then under 10 cameras for the whole area servicing hundreds of homes. Further should you wish that the security company monitor cameras inside your home the set up and monthly costs are for your pocket. (it will then run off your cap(if you have) and the line speed you pay for first before affecting your neighbours.)
Thanks for the info about number and placement of cameras. Street cameras apparently learn registration numbers and alert when suspect vehicles enter the area (what criminal keeps the same reg number?) but if they're carefully situated they would help. We're already paying almost R1000.00 p.m.

and cameras would add to that.
The security company offer to wait at your gate if you ask them to and have 3 dedicated vehicles in the area but somehow crime still happens. Their response time is usually 2/3 minutes but they didn't arrive when a resident was accosted inside his house recently by 4 armed men who climbed over his palisade fence.
Local break-ins have all been by pedestrians. Security persons are not allowed to accost them - that seems to be the job of local police.
The area is RELATIVELY safe (if you can say that in Johannesburg) but as a group we're keen to up security.