If you're looking for the standard 5.5mm x 2.1mm DC plug & jack, usually the standard for 12 volts DC, like the image below, they can be found on amazon.com ==>>
here. Both male (shown, usually power supply end) & female (usually camera end) are available. Also, they abound on eBay as well.
I used to see similar plugs & jacks on PLC (Programmable Logic Controllers) interfaces, along with many DIN-rail accessories. I think they were from
Phoenix Contact but items like that are usually in bulk, from a distributor and are very expensive, so I would do as you: cut it off and hook up one of those as in the image, insuring I had the polarity correct (12 VDC cams in USA have + on center, - on barrel).
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