It's actually really easy! And smells great! And so far seems to work well; the only downfall IMO is that it separates, so I have to shake up the bottle really well each time I use it. Not a big deal for the money I'm saving. It costs about $2 per 5 gallon bucket-full. You need three ingredients, which I found at Winco, plus the bucket.
After I use up my 5 gallons, I plan to try the recipe for the powder detergent. I really prefer liquid, but the dry might be simpler; less stirring at the beginning and then I don't have to shake, shake, shake it so much.