Laundry detergent. That is what got us started. Just starting out in life with one job between the two of us, when a friend of mine tipped me off that you could make your own (very effective) laundry detergent for MUCH cheaper than what you buy in the store (and it is much more eco friendly).
We started making it, started using it, and we really liked it! Plus to learn that it costs us about $1 per batch, and a batch is 2 gallons....there was no reason why not to keep using it, right? The big sell for us was when we were walking through Sam's Club and saw a "bargain container of Tide. 2 Gallons for $20. Remember what I just said, how it costs us $1 for 2 gallons? that's a 95% reduction in cost. That's a big deal.
Well, when we ran out of dish soap, we decided we should see what we could find online as far as recipes that we could make from things we had at home. Eureka! Again with the eco-friendly much cheaper homemade products (I should note that we cut the proportions by 3/4, and that we replace the not-as-eco-friendly octagon soap with Ivory, like in the laundry detergent). Then toothpaste, then fabric softener. Then I got smart and read the box of Arm & Hammer Super Washing Soda, and you can do sooooo much more with it! We can wash our whole house with inexpensive eco-friendly products. How fascinating is that??!
I'm pretty excited. It always infuriated me that "Green" products were so much more expensive than the non-earth friendly ones. I'm so glad that I can save money AND be a better steward of this planet that we're on.