I currently use 2 setups like this for most of my casual portrait shoots. I want to stress this is a basic setup. You won’t get the same quality as you would with monolights, studio lighting, reflectors, etc. However, this is intended for a different purpose.
I use Nikon SB-600 speedlights. These are a bit dated, but still work great. I almost always use them in manual mode as I like to control the amount of light manually. I’ve been tempted to upgrade to SB-900’s, but honestly for what I do the SB-600’s are fine. Also, the SB-600’s are inexpensive. Easily under $175 used.
I trigger my flashes with a set of Elinchrom EL-Skyport universal receivers. These are low profile and are perfect for the setup. I can’t plug the Skyports directly into the SB-600’s so I have a simple Impact male synch cord mated to a hotshoe. I’ve put some Velcro on the side of the speedlights and on the bottom of the receivers so I can stick them together. Or you can simply let them hang which is how most photographers seem to do it. The Skyports are triggered with an Elinchrom universal transmitter.
If you have Nikon speedlights you really don’t need electronic triggers. You can fire them using Nikon’s Commander Mode, where the camera’s pop-up flash triggers the speedlights. I don’t bother since I like the Elinchroms.
I use Manfrotto 5001B lightstands which are extremely portable. Very light and can easily handle the weight of my setup. On top of the lightstands are mounted Manfrotto swivel umbrella adapter tilt heads. These are great with or without umbrellas. Finally, I mount a Frio coldshoe on top of the adapter tilt head. I snap my flash unit onto the Frio and I’m good to go.
For portability I am using a LumiQuest Softbox III most of the time. I will use umbrellas occasionally, but for most of my setups the Softbox III’s work great. I attach them to my SB-600’s with a LumiQuest Ultrastrap (although any velcro strap will work).
So there you go. Not fancy by any means, but efficient and effective. Two of these setups go with me anytime I need portable lighting. I have a simple Manfrotto lightstand bag that I keep the stands and umbrellas, and the rest goes in my camera bag.