Run, do not walk, to your library or bookstore and get a copy of Cheaper and Better: Homemade Alternatives to Storebought Goods by Nancy Birnes.
It literally has homemade recipes for everything from Kahlua to bath crayons for your kids. Every recipe uses household ingredients and includes a cost comparison, telling you on average how much you'll save making your own (the safety and health factors involved in staying away from processed crap, of course, are priceless). I wish I'd found this earlier - it would have saved me hours of scouring the Internet for recipes exactly like these!
[Note: Proper credit must be given to the amazing Patrice Lewis who first alerted me to this book by posting one of its recipes on her blog. Thank you for sharing, Patrice!]