There are a number of reasons that you might want to use elearning for your employees or customers but one of them is cost.
If you regularly do classroom training, or training by webinar and you are always covering the same topics, elearning might be something to consider.
To work out whether it is cost effective, get a quote on the development of the elearning first. Most developers will give you a free quote, or at least an estimate. Then work out what the classroom or regular training is costing you. For online training, it is usually just the time that your trainer spends preparing for and conducting the training as well as any follow up time. For classroom training, there may be other costs such as room hire, food, travel costs for participants and the cost of any printed materials.
Now, multiply those costs by the number of training sessions you would run in a year and then compare them to the cost of elearning development. You should have a reasonable comparison.
But remember there are many other reasons to use and not to use elearning such as interaction required and course content and all of these have to be considered along with cost.