Do a search in Vinyl Asylum under "cleaning fluid DIY" and you will find many different recipes. One of the more common is:
"Here's Harry Weisfeld's recipe (the VPI president, who seems to prefer it over the VPI fluid they sell!). Put 16 oz. of isopropl alcohol in a gallon bottle, fill the bottle with distilled water, add approx. 8 drops of Dawn dishwashing liquid as a surfactant, and use it happily. I do, works great."
The recipe that I have used to clean 8,000 LPs is 40% isopropyl alcohol, 60% distilled water, with a few drops of Kodak Fotoflow as a surface tension reducer and a couple of drops of pure ammonia window cleaner.
These DIY solutions will do fine for getting the record clean enough to hear if it is a 'keeper' or not. If it is a keeper, then you can always go back and use one of the proprietary fluids to get the last little bit of grundge out of the grooves. If it is not a keeper, why spend the money?