Marinading steaks is a great way to enhance the dining pleasure of the meat, but don't just think of marinading meat(steak) in one way, depending on your mood you can enjoy steak many diferent ways.
Dry rubs are fabulous and are easy to make. Even with a lightly stocked spice cupboard you can make a great rub. Some of the mainstays are Sea salt, coarse. Paprika, Cayene, garlic powder, onion powder and a pepper mill.
A wet marinade can also be made straight from the cupboard and fridge. All you need to do is stock certain items and away you go. As with above; lemon/lime juices, tabasco, olive oil, red wine vinegar, balsamic vinegar. buy fresh herbs and garlic when you are making a marinade. A small food processor will make thing really easy as well.
As stated by others many store bought marinades are good, but you cannot control the sodium or fats that go in them.