think about it though for a second. Now i sell PC based myself, as well as stand alone embedded DVRs, mostly the GE DVRs though.
Any PC DVR, even the $99 card needs a decent PC if you are selling it to a client and giving a warranty on it, other wise welcome to the world of PC service, and alot of it.
Therefore even if you pick out the parts, and build it yourself you are looking in the range of around $600-700 for a decent starter PC for a dedicated DVR system.
Add time to phyically build it, load windows, the other software, clean it up and tweak it, then at least 24 hours burn in time. You are then well over $1000 for the PC alone.
Next add a decent PC DVR Card, say a 16 channel 120fps at $400 for example.
Then, add time to show the client how to use it, as most PC DVRs, from lowest end to highest end, can take some time to learn. I can install a stand alone in 5-10 minutes and client knows how to use it. A PC based DVR, forget it, and if they arent PC literate, good luck.
PC DVRs are good for high speed recording and easy upgrades of Hard Drives. Stand alone embedded DVRs are good for plug, play, and forget, easy install and simple to use, DVRs.
Personally I dont sell them only because I sell high end. Otherwise they are very decent decent DVRs with as much features as most people ever need.
AND, if you want a stand alone embedded plug and play DVR that doesnt crash and is the ultimate cheap one on the market, try the AvTech units, they have been around for a long time, and trust me, i have 1 here right now AvTech sent me to test (that means test only and review it), and several 16 channels that we have tested to the max, and even installed, and nothing I can do will crash them. They are budget, and very little features, but, they are cheap, the ultimate budget DVR that actually works. These are the ones with LAN for remote video by the way.
Ones that have crashed after only minutes of testing - Neverfocus, HiSharp, and Provideo.