For each detergent I weighed two samples and then dried them to constant weight to determine the concentration, the 'percent solids'. Because detergents dry to a waxy solid I absorbed the samples onto paper towel to avoid the possibility of water droplets getting trapped. (see pic)
I also weighed a 250ml sample of each detergent to get the density, so I could report both the percent solids by weight and the grammes of solid per litre. These are shown in the table. I've also shown 'equivalent volumes' which shown volumes of each which contain the same amount of detergent. This should give an idea of where to start if you are using a different detergent from the one in the recipe.
Finally I calculated the unit price per litre and per gram of solids. These are only approximate since prices vary from store to store.