I've been exposed to many switches over the last 30+ years in the IT business, and all the hubs and splitters that existed before switches. I would strongly suggest you use as few switches as possible to minimize your uplinks. Given the budget, I would be looking at the Netgear GS752TP for around $675 online... 48 POE Ports, and 4 SFP Ports..... 384 Watts... POE+ on 8 ports
and the 24Port Version GS728TP 24 Poe ports 8 POE+ on 8 ports, plus 4 SFP slots.. circa $425..
totalling 576 watts accross 72 free Ports. Use Fiber or copper SFP Modules to build a 2G LAG between the switches. If your video recorder supports bonding or teaming the NICS, use two SFP modules to feed the GS752TP and the primary switch....
Netgear includes a free SNMP / FIRMARE / BACKUP management tool, that's works fine for the basics. It's not a full management tool like ManageEngine Utils, but good enough to hint in the direction of trouble. I believe the warranty is Lifetime too....
I also think you can enable Sflow using a command line on most of Netgears L2 managed switches.