Just because you can buy shampoo and makeup at the local supermarket doesn't mean that you should. If you care about your appearance, it's a better idea to find a beauty store where you can find all the very best products in one fell swoop, from mascara to mud-masks.
Don't expect the prices at your local beauty store to be cheaper than what you'll find at Wal-Mart. The fact is, a beauty store usually stocks the very best products, stuff that you won't find in the discount stores, so you should expect to pay more for the quality.
While they may not be licensed cosmetologists (though they may be), your beauty store's employees can certainly advise you on the proper makeup and other care products to use for your coloring, skin type, hair type, etc. Don't be afraid to take advantage of their experience.
