I don't know why anyone would think that they have to use HE detergent. If you think you need to do that, instead buy one bottle of it. Empty it through use. Go to Sam's, or another wholesale store and buy a huge bottle of detergent. Fill the HE bottle half way with water and half way with regular detergent. There, now you've made HE detergent at 1/2 the cost because all you're paying the same price for is more water in the bottle. Plus, you get the advantage of having it in the HE bottle that evidently you think that you need.

Oh, and I refill smaller fabric softener bottles with 1/3 fabric softener and the rest water so I don't have to measure that. I just fill up the reservoir straight from the bottle.