Ultimately it seems speedlight+diffuser seems to be the most popular choice. I have WJ-60 continuous ring from yongnuo, but hardly use it for macro because its not quite that powerful, but otherwise useful for light painting. For $20 its a very handy flashlight to own.
BOOM! ringlights are a bit overrated. a simple speedlight and diffuser/small softbox is the way to go. get it off camera with inexpensive slaves and its great.
flash-any of these will do
| ThePhotoGadget.com
Id suggest if youre getting one, get one that will do TTL and manual, not only manual so u can use on camera as well.
slave-
Yongnuo RF-603 II Wireless Flash Trigger Set for Nikon N3 | ThePhotoGadget.com
I dont have affiliation with the seller. just have bought some slaves and flashes from him. u can find the same from ebay and amazon. you choose.
softbox-
Mini Portable 9" 23cm Softbox Diffuser F Reflecter Flash Speedlite Speedlight | eBay
just giving an example but you can find bigger or others. the selection is huge. just typed in mini softbox. if youre shooting out in the heavy contrasty sun overhead, a reflector may be better to soften and difuse the light so you dont get hard shadows.
60cm 24" Photography Studio Translucent Collapsible Light Photo Reflectors | eBay
you can find five in one (gold/silver/white/black/translucent) like this which is good to have also for outdoor portrait sessions.
when I buy, I always try to buy tools that will let me use them in many different styles of shooting and situations. so no "specific" tools.
oh and if you need to mount the flash and youre traveling light, maybe a mount
large flexible tripod | eBay