Surprisingly, there is a very easy and effective way to save money on dish soap by losing less to waste, and using less for dishes. And it is quite inexpensive or even free to start doing!
Purchase a large pump-action bottle (such as the kind used for hand soap) or re-use one of the larger economy sized hand soap containers with a pump. When you use a pump, you are much likely to use less (since you have to pump for each squirt, as opposed to doing the long squeeze with a regular dish soap container) and you will lose less soap dripping down the sides of the container, like what happens with the regular bottles.
An added bonus is you can also purchase the large economy bottles of dish soap, and fill up your pump dispenser as needed.