I admit that my Dell tech experience is more than a decade old at this point, so they may have improved on the binning of the parts that go into their lower end systems, so I will have to defer to your more up-to-date experience there.i7-6700 can be purchased for just over 400...an i7-7700 at about 500 or so....you are hitting those numbers with the processor and windows os alone..
heck, my hp elitedesk was 400 - i7-6700, ssd (256)...8gb memory...
there are NO support issues with the dell optiplex and elitedesks...I run 20 blue iris systems and support an additional 50 pc's that are made up of optiplex and elitedesk...never had a failure...ever...my only hardware failure was a lenovo home based laptop...my other lenovo laptop has been running 24/7 on a reception desk for camera viewing for at least 4 years now...non stop...
As for the systems, I just did a search on ebay, and the cheapest i7-7700 system I could in a broad search under desktops and all-in-ones was $575 and I'd still have to add more for a boot disk. Of course, my timing may be bad and all the good deals may have been snapped up already. I know systems come and go... they may add new systems tomorrow that are better/cheaper. But just in case, I also did some searches specifically for elitedesk systems and since there were no i7-7700's, the cheapest i7-6700 (non-T) I found with 8GB RAM and 256GB SSD was $756 (Elitedesk 800 G2.) Doing the same for Optiplex netted an OptiPlex 5050 w/i7-7700 8GB ram 256GB SSD @ $879.98.
The systems directly on the Dell site are more expensive... the cheapest pre-configured system with an i7-7700 CPU on the business site is $880. I found one on sale on the home site for $779. I tried to customize several of them to see if I could get the price down but none allowed changes, and I couldn't find a custom configurator... when did that go away? It used to be that you could dial in the specific system you wanted to custom order.
The system I picked out has a micro tower case I like, a quality MSI microATX MB, i7-7700, Kingston HyperX 8GB, Samsung 250GB M.2 SSD, and a Seasonic PSU, for just under $600. I could easily shave off another $100 or so if I wanted the lowest price on every option too. CPU and SSD were the two largest chunks. Though that would be an amazing plex system, and should run a dozen cameras easily once I throw a WD Purple HDD in there. Heck, throw a discrete video card in there and it would make a decent gaming rig.
In any case, while I'd love to find a $300-$400 PC that suits my needs, chances are I'm looking at at least $500 if I can stumble on a great online deal. But I can build the system I chose any time... and maybe get it cheaper if I stumble on some deals on the parts side.
That is, of course, assuming I end up going with a PC-based VMS system. I'm leaning that way, but still don't know that it really adds a ton of value over an NVR appliance which can be had for well under $300.
I appreciate your input... thanks!