I built the box below for Ecomm, Field Day and using it at my camp. I got parts from many different places. Don't limit yourself to just one supplier.
Very nice Kit. Pretty pricy too hi hi.
I have found that if you cannot build a kit like is shown in the last post, one very good way to make a great kit is to have several soft bags and a couple hard cases.
You can put take apart antennas, tripod(s) and poles in one or two soft (baseball bat type) bag, have a box with cables, coax, wire antennas and other items. Have the radios, power supply, TNC etc in a couple hard cases and carry a smaller bag with all different types of fittings, power pole connectors, a few different ga rolls of wire and crimp tools. Some wood boxes with batteries secured, in the box with power pole connectors on fused wire leads that easily come out of the boxes already hooked up to the batteries. Power pole connectors on wire to the batteries for charging or solar panel hook up, already to go.
You can find soft bags to fit most anything you need; things not easily damaged. The hard boxes are padded for your expensive radio equipment.
The main thing is to have everything ready to be quickly hooked up. You can color code coax and wire ends, have all the fittings already put on each coax and wire and roll each up. The trick is to make fast work of connecting without making mistakes. Extra coax, fittings, tape, 12V and 120V soldering irons and solder, guy rope, wire, clamps and tools will always be needed. If not by you because you prepared, someone else will need something or you may have to repair something of your own.
I give a lot of credit to the person who made the all in one box, but it's something not all of us can do. Breaking things into groups, labeling everything and proper packing will insure that you have all you may need. It can be quickly deployed and set up. You have extras because it's always that one thing you forgot or no fuse that causes delays or failure.
If you have an antenna analyzer, they are great to have it getting antennas set up resonate as fast as possible. Have the antenna pre built will almost always have you very close. A multi purpose meter is another thing. Plenty of batteries and flashlights. Portable 120 V lighting is great if you have a generator and room to carry it.
Put your solar panels on fold up stands, ready to plug into the controller, make the fold up so when it's closed, the panels are protected. A fold up table and 12' X 12' push up topper with a few chairs are great to have if you have the room.
Take time to think about every possible thing you may need. Put things in different packs so things you know won't be needed do not take up room in your vehicle. This has worked great for me and even given me some extra choices when it comes to antennas.
It can be simple or you may have a lot. This all depends on you and what will be needed as well as the amount of money you want to spend. I sometimes (where possible) duplicate the important things in different packs so I don't have to take a whole pack for just a few things.
A back up power supply can be a lifesaver. One of the 36 amp one's on EBAY for $70.00. They work great, lots of amps, are small and make a great back up. I never take just one power supply.
I have the room, so I tend to take more than I need many times, that said, it has also been a help to others. The fun is that you can make your go kit anything you want it to be. Whatever you decide, give it a great deal of thought. You can get to the point you are taking way too much or not enough. Take some cash, enough to eat and buy fuel to get home, the ATM's and credit card machines may not be working. Only you know what you need and much depends on what you know about the call out, distance from home and hardware stores, time you'll be out and many other factors. Don't forget food and drink, bug spray and all medicines you take. Some tums if you eat my food would be good also.
Last, if you can find a decent travel trailer for a good price, they are great. If cared for, the older one's can be found pretty cheap. Stay on the smaller side. You have a place to store things, sleep, stay warm (or cool) and dry, cook, shower, poop, they are fantastic for call outs where you can get one to where you are going. If you get a trailer, service the wheel bearings often and carry two spare tires.
Keep good tires on it or blow outs will happen every time. That old ounce of prevention thing. I have a Toy Hauler (not cheap), but it's almost like being at home. I love it when we go on the three day excersizes, and so do the other guys. You don't need to spend a lot to find something that will do a great job for you. I'm too old for that roughing stuff anymore, been there, done that. You know, it's time for that Golden Years stuff.
Before taking a travel trailer anywhere, be sure there is a place for you to park it. If it's a bad area, you may not want to take your trailer, better to stay low key and ask for permission first.
I know I sure don't want to roll up in a nice outfit in the middle of a mean crowd looking for food, water and anything else they can grab. Know what you are getting into, where you are going and if it's even possible to get something like a trailer into the area. You do no one any good if you can't get there or are an additional security hazard. A trailer can be a problem, not an asset in many cases, check before hooking one up to your vehicle, if unsure, leave it at home and just pack your vehicle.
It's not a contest of who has the best or most, it's having what you need to get the job done and do it quickly without running into a lot of problems. The extras are not to show off, but to help others. That's what we do. Not everyone can afford or even wants to have everything, but if you have what will be needed, your ahead of the game.
If you show up with a handheld radio and a few extra batteries, you will be welcomed and I have no doubt will be an asset to the smooth running of the operation.
Sometimes when new, we tend to take way more than the call out may need. Having the all the extras is great, but the extra weight uses more fuel, makes it harder to get going quickly and a host of other problems. I have listed quite a few things. I don't take everything I listed every time I go, but I do try to find out what may be needed by finding out as much as possible about what type of call out we are going to, how long we may be there and what kind of assistance is needed. Then I can decide just how much and what would really help, not just look good. It's not a who dies with the most toys contest.
Last, to answer your question of sources. As others have said, you will not find everything you need at one place. Many small things can be bought cheaper at a non radio store. If you buy from several places, try to spread out the prices to add up to the mark for free shipping if your getting a lot. You don't have to do it all at once either.