I know many of you will already be doing this, or at least know about it, but cooking in a saucepan with a steamer on top is a frugal and nutritious way to prepare your daily vegetables.
I bought this set of three saucepans plus steamer about ten years ago and I use the steamer a few times every week. I put the hard vegetables, such as potatoes, carrots, turnips etc., in water in the saucepan to boil, and softer vegetables: spinach, cabbage, broccoli, cauliflower etc., in the steamer on top of the saucepan. The lid from the largest saucepan in the set fits the steamer.
Put the boiled vegetables on first and cook, with the lid on, for about half their total cook time. Soft vegetables take less time to cook so add the soft vegetables in the steamer half way through, and with the lid on, finish off the cooking time.
You're using the same amount of energy to cook two vegetables instead of one. This will save you money and the steamed vegetables will retain slightly more nutrients than boiled vegetables.
If you don't have a steamer, don't rush out and buy one. Have a look at what you already have and see if you can make do with that.
Another way to save money when cooking is to bring the vegetables up to the boil, then immediately turn them down to simmer - always with the lid on - it retains the heat in the pot.
Many of the ordinary daily things we do everyday, the money or energy saving things like this, save a very small amount of money that you might think are not worth worrying about. You have to look at the bigger picture though - look at those savings over an entire year, then they add up and make sense. You have to make the effort to do those little things every day to make a difference, and soon they'll become second nature to you.