I think you have to experiment with various products to find ones that work for you and your customers. Once you have found the right products, you can search online for the best prices. I use Ebay, Amazon and Overstock for most things.
Of course, it depends on what kind of cleaning you do. I do home cleaning. Commercial cleaning may be a lot different, as you may be dealing with a lot of square footage.
I am considering buying some sort of steam cleaner, as many of my customers have tile floors. You shouldnt use this kind of mop on hardwood floors, or laminate, because it may cause buckling of the floor. But on tile, it can be a super good tool.