Sometimes. Larger companies will not do that since it makes the places that sell most of their things mad to have to compete with the manufacture. (or sometimes they intentionally price such that others can undercut them).

Mostly I don't do this because I don't know which company makes the one I want. An independent third party that knows the product and sells several different versions from different companies can help me select which one is best for me. This is a valuable service - when you can find it.