(Caustic, when mixing your detergent be sure to ventilate well and do not breathe in the dust.)
I mixed:
8 lbs Borax $6.68
Around the house, borax can be useful for cleaning and laundry brightening.
12 lbs Washing Soda $13.60
In laundry, washing soda accomplishes several things. The high alkalinity of washing soda helps it act as a solvent to remove a range of stains, and unlike bleach, washing soda does not usually stain. It is also used in detergent mixtures to treat hard water; the washing soda binds to the minerals which make water hard, allowing detergent to foam properly so that clothing will come out clean, without any residue.
4 lbs TSP $8.00
The major use for trisodium phosphate is in cleaning agents. The pH of a 1% solution is 12, and the solution is sufficiently alkaline to saponify grease and oils. In combination with surfactants, TSP is an excellent agent for cleaning everything from laundry to concrete driveways. This versatility and low manufacturing price, made TSP the preferred basis for a plethora of cleaning products sold in the mid-20th century.
2 lbs Sodium Percarbonate $8.00
Sodium percarbonate is an oxidizing agent and ingredient in a number of home and laundry cleaning products, including eco-friendly bleach products such as OxiClean and Tide laundry detergent. Dissolved in water, it releases hydrogen peroxide and soda ash.
2 lbs. Citric Acid $4.80
The largest industrial application for citrates is the detergent industry. In powder detergents sodium citrate contributes alkalinity to enhance surfactant performance. The environmentally friendly nature of sodium citrate is a major factor in the use of citrates in the detergent industry.
1 lb Soda Ash $3.00
The home can benefit from the presence of soda ash in the laundry room. The addition of the soda ash prevents hard water from bonding with the detergent, allowing for a more even distribution of the cleaning agent during the washing cycle. In addition, soda ash has demonstrated an ability to help remove alcohol and grease stains from clothing, which can make the entire process of doing laundry a little less taxing.
(Truthfully, I didn't set out to use soda ash. In my quest for sodium percarbonate I was assured that soda ash and sodium percarbonate were one and the same. They are not. Soda ash is sodium carbonate. Both are used in cleaning products, but sodium percarbonate is the active ingredient in oxygen cleaning additives. Since both are used in cleaning products, and I had already spent the money for it, I have, in this batch included soda ash.
29 lbs of laundry detergent $44.08 This is a full strength laundry detergent without the use of fillers. It also contains oxygen cleaner for extra cleaning power. 1/8th of a cup does the trick. At 1/8th of a cup at a time 29 lbs. of laundry detergent ought to last a few years!
UPDATE: I've been using it for a year and 4 months now and it's not half gone. I also use it in my automatic dish washer (half of an 1/8th cup coffee scoop does the trick!) My dishes come out clean and without any haze. :)))
Sources:
http://www.wisegeek.com/what-is-borax.htm
http://www.wisegeek.com/what-is-washing-soda.htm
https://en.wikipedia.org/wiki/Trisodium_phosphate#Cleaning
https://en.wikipedia.org/wiki/Sodium_percarbonate
http://www.apacchemical.com/CitricAcid.htm
http://www.wisegeek.com/what-is-soda-ash.htm
hmmmm, how does a mom know these things? 
