When you call or email an SEO/SEM company you are connected to a sales person whose job is to sell you the inventory/products/services the company has on hand, regardless if these will help your companies meet its marketing goals. The fact is, if you use an outside company to handle your SEO/SEM activities you could be paying up to 10 times more than you have to without getting any better results than you could get for yourself.
In the past if you wanted to do your own online marketing it would be a really big undertaking and you could face some real danger too. You could go out to various forums and websites and ask individuals you don’t know to trade, sell, or rent you links. This could have you sending money out to people you don’t know who live somewhere in Pakistan or East Asia.