It's true that you can buy cheaper soap at the grocery store. But if you want the good stuff, that doesn't dry your skin out, it costs more--so why not make your own?
When you think of making your own soaps and lotions, you have several options. You can make your soap from scratch, using raw materials, and the cold process or hot process method. You can make your own lotion from scratch, using raw materials. You can purchase melt-and-pour soap bases and add colors, fragrances, and/or other additives. And you can purchase lotion bases and add fragrances and/or colors.
Personally, I gave up making lotion from scratch a few years ago. I just wasn't getting the results I wanted. After experimenting with sample lotion bases from my suppliers (listed in the Soapmaking Resources at the right), I found a couple bases--one for lotion and one for cream--that I really like. I usually purchase a gallon of each base at a time, then make up enough to fill 3-4 bottles or jars (also available from the resources at the right) each time. Sometimes I leave them unfragranced, sometimes I add fragrance.
What do I, personally, use for lotion and cream bases? For lotion, I like the "Lotion Base- Gallon" from Bramble Berry. Its first ingredient is aloe vera, so I know it's good to use after I go out in the sun. If you don't use too much, it soaks in quickly and doesn't feel greasy. And it gets rid of the middle-age crinklies on the backs of my hands (something my from-scratch lotion never did). For cream, I like "Body Cream Base" from MMS. I don't use it on my hands during the day because it does leave a little bit of a greasy feeling. But I put it on my feet before going to bed, and it is wonderful for keeping the skin on my feet moist and supple. It's also great for rubbing into dry knees or elbows. All the suppliers I've listed have a variety of bases.
Now, for soap. I make my own soap from scratch. Really, it isn't hard to do. There are lots of resources available: books, tutorials on the Internet, and mailing groups. I'd suggest Googling "soap making" and reading the sites that come up. If you're interested, I'd recommend getting a couple books (or more!). The Soapmaker's Companion, by Susan Miller Cavitch, has been the the bible for soapmakers for a long time. While I don't agree with everything she says, this is an excellent resource. Smart Soapmaking, by Anne L. Watson, is a great resource, but it shouldn't be your only book on soapmaking. She has a radical method for telling when the soap is ready to pour into the mold. I haven't tested her theory myself, so I don't know how good it is. I still rely on the method of pouring at "trace". The Everything Soapmaking Book, by Alicia Grosso, is also a good resource for the beginning soapmaker. With any soap recipe from a book or the Internet, it's a good idea to double-check the amount of lye to use (every author makes mistakes, and some books are known for printing lye-heavy recipes). Bramble Berry and MMS both have good lye calculators, and http://www.soapcalc.net/calc/soapcalcWP.asp is another good one.
If you make your own soap from scratch, you need to deal with lye. You can't make soap without lye. If you use melt-and-pour to craft soap bars, you don't have to deal with lye. But the manufacturer used lye when they made the melt-and pour. So don't believe soap crafters who tell you their soap is better than cold process because it doesn't contain lye. Whether you make soap from scratch or use melt-and-pour soap base, there isn't any lye left in the soap. It has all reacted with the oils and fats you added to make soap.
There are soap artists who make absolutely stunning soaps with melt-and-pour bases. I rarely use melt-and-pour myself, though, because I prefer cold-process soap. But you can make beautiful soaps that are better than what you buy in the store.
Back to the subject of lye. You have to take precautions, which I'm not going into here. But the books listed above do discuss how to safely handle lye, and most on-line tutorials also discuss it.
Because dissolving NaOH in water to make your lye is an exothermic reaction (it generates heat--quite a lot of it), and you want your lye no warmer than 100° when you make the soap, many people mix their lye the night before and let it cool overnight. If you do this, be sure no one can accidently spill it or drink it. Years ago I was on a mailing list with an experienced soapmaker you did this. Her husband got up in the middle of the night to get a drink of water. Because he was half asleep, he forgot that the pitcher on the counter was filled with lye. And he poured himself a glass of lye instead of a glass of water. He survived the experience, but his mouth, throat, and esophogus were horribly burned, and permanently damaged. The moral of this story: Be Very Careful with Lye!
Now that I've scared you about lye, let me say that it can be handled safely. You just need to be careful. You can't go on autopilot with lye. You have to think about what you are doing.
So, why would you want to make cold process soap? Because you can make a rich, creamy, soap that doesn't dry your skin out, and that smells better than anything you can buy in the store. If you want to go the natural route, you can use essential oils to fragrance your soap. Or you can use one of the many [non-natural] fragrance oils available for soapmaking. Personally, I almost always use a fragrance oil.
As a teaser, here are some pictures of soap I've made.
So, what about storing your soap and lotion? They should be stored in a cool, dry, location just like your stored food.
I have soap that has still been good 5 years after I made it. The fragrance was mostly gone, but the soap was still good. So you can make several batches of soap and store them wherever it's convenient. If you cycle through your stored soap as you do your stored food, you shouldn't have any problems. You probably shouldn't store it too closely with your food. Your food should be sealed so I shouldn't pick up any fragrance from the soap, but it's better to be safe than sorry.
You have to be more careful with stored lotion. Most of the manufacturers say their lotion should be used within a year of the date purchased. Kept cool and dry, lotion can probably last longer than that, but you never know. Remember that lotion is a wonderful environment for growing bacteria, molds, and funguses--that's why they require a preservative. I don't store as much lotion as I do soap. I'd recommend keeping at least a few month's worth in storage, and cycling through it as you do your soap and food. I keep mine in the gallon jugs, and only make up (add fragrance and put into bottles) a few bottles or jars at a time.