Any flash(es) will work. Use it like any studio flash. You can buy radio trigger to put on camera and radio reciever for every flash, or IR trigger and photo-cell for flashess, I think it is cheaper than radio solution. Or, you can use Nikon flash on camera in manual mode to trigger other flashes, and other flashes can be any brand.
If flashes with flash output regulation is too expencive, you can buy even cheaper flashes without output regulation, and controll flash output with moving flash closer or further from subject.
For example I bought IR trigger for 20 USD and photo-cells with flash hot shoe for 5 USD each and used that combo with my Canon EOS3. Flashes I used had not power regulation and were not Canon dedicated...
Of course in both cases you will have to use flash meter or if you know flash output (Guide number) of you flashes, you can calculate how to position your flashes (or if use flashes with output regulation, what flash power to set).
Basically, use flashes like any studio flash.
And for price of dedicated flash (Nikon or Canon or...) you can buy secondhand (or even new) real studio flashes (monoblock). Getting camera flashes (dedicated or not) is good if you shoot on location without electric power source, and not need power of real studio strobe.
P.S. Just remember to use X sync speed of your camera

In all manual non dedicated situation, you of course lose all automatization and must use head
