While it may seem a fundament of contemporary smarts that design and marketing is more of a commodity and it doesn't matter who does it, in reality the story is more complex. Likewise, the savings of doing it yourself or in-house may be more of reflex and less of a reality.

This will likely clear up why even huge companies that can afford all sorts of in-house departments, frequently hire outside agencies.   

Here are the pros and cons of
do it yourself or in-house:

pro:

• familiarity with the designer
• communication very easy and always available
• can shut down project easily
• easy to check progress
• designers familiar with company style

con

• you are accepting your own or the in-house designer's skill range
• no contract for project guidance
• designer may rely on repeating in-house or personal style
• designer may rely on what's easy for them or what's known to be accepted
• designer less likely to try something different or daring
• in-house designer may be restricted by in-house politics
• pleasing yourself can get too easy
• too easy to work by the hour, not the problem