Well there's a lot of options, from the very cheap, to any amount of money you want to spend. It really depends on what you want your end result to be. Here's some questions to help you towards your solution before you spend extra money.
First, what is your budget?
You can safely carry models in a hard case container with foam trays and a strap for as little as $30. Or, you could go for broke and get yourself a custom tray loadout with some really beautiful bags that are water resistant, have lifetime warranties and will last forever.
Second, how are you going to be carrying this transport and where will you store it when not in use?
Are you going to need to use a bicycle/motorcycle to get to the event? Or, are you like me and driving a car that's got a lunchbox for a trunk (my miata...) Perhaps you have all the space in the world? Finally when you are home, where are you storing this transport?
Third, do you mind putting in some time, or are you impatient?
This one is straight forward, do you mind using a little ingenuity and don't mind a homespun result or would you rather let someone else do all the heavy lifting?
All these things considered will help you make your decision, so let's review some of the solutions. By no means are these "be all end all" solutions, and many of the answers can be mixed and matched, but hopefully this is a good starting point.
Solution 1 - Going to your local large scale retailer (these are your Target/Kmart/Walmart types) and buying a can cooler. Then you'll hit up your local fabric store or upholstery shop and buy a bunch of chair foam. It's open celled and easy to work with. This is your $30 - $50 solution to carry around 1500 to 2000 points worth of troops. I have two of these bags for all vehicles and bigger items, books, dice, writing implements etc. They're really cheap, certainly not guaranteed against damage or wear and don't be surprised if you get asked if you really needed to pack two lunches. Not glamorous but quite effective.
Solution 2 - Going to your local hobby shop and buying a preset generic hard case. This comes along the lines of Army Transport or the Games Workshop hard cases. These have generic foam trays with rectangles for you to place your normal troop types. There's options that are soft bags, with multiple foam trays which are so cheap you don't mind cutting away dividers to fit items larger than a one inch troop. e.g. space marine bikes, or fenrisian wolves. There's also larger cases for more troops/vehicle, but they are either very thick, to downright big. (The biggest option from Games Workshop comes in at 120 troops, and about four to five medium sized vehicles, but looks like you're carrying an easel.)
Solution 3 - Ordering online from a resource that will setup custom trays for you with awesome bags to carry them in. The leader in this type of setup is without a doubt Battlefoam. They're going to ask for a bit more "capital investment" than normal, but sales and specials are going on constantly, so keep an eye on their site for them. They're going to provide you with custom setup trays that will carry for example a monolith with two ghost arks/doomsday arks in one tray. An impressive feat once you cut your own foam trays. They're clean cut, and very, very professional. People know you're not messing about and care for your models.
|Hard case and soft case with trays, the Rubbermaid/Tupperware mega solution, and troop trays.|
In summary, there's a few options out there. More often than not folks buy a can cooler of appropriate size, then buy foam trays from Battlefoam, still others buy an Army Transport bag at their hobby store and buy chair foam to fill it. I've even seen chopped foam and Tupperware as a transport. The question really is up to you, there's a lot of ways to get your army there safe and sound so how much money to time ratio are you willing to spend? Only you can answer, and best of luck on your endeavor!