I'd really suggest not buying anything until you've spent time with the device and you understand how you're most likely to use it. There's no point in spending money on a big tub if you're only ever going to cook one or two steaks. Similarly, if you're likely to be doing lots of long and low cooks then an insulated box with a lid is a good move. But there's no need to go overboard. I use an old, antiquated tartan cooler I found in the garage. It works a treat and cost me bupkis.
Similarly, don't go out spending hundreds of dollars on a cast iron pan. Hunt through rumble sales and yard sales. You're bound to find an old one that just needs a bit of TLC. I spent a whole 50c on a 12" cast iron skillet at a farm clearing sale. I could tell it was old, probably belonged to the retiring farmer's grandma. It was covered in surface rust, but all it took was a bit of elbow grease and some fine grade steel wool and I have the best quality cast iron skillet you ever did see. When I need size and heat retention that's what I use. If I'm looking to be quick and dirty I use a 10" carbon steel one of a similar history which I can throw around with no fear of damaging it or my toes.
The point is: Learn first, buy later. You'll finish up spending less money in the long run.