For me, compensation is not the biggest motivator.
Other things come first.
One--I have to believe in the products/services I am selling and the company I am selling for.
For example, if I see a company filled with signs of instability that I cannot impact; I would not be selling for them. This can come from issues with ownership, management team, business practices, or a complete lack of strategy.
Likewise, if the product or service is not something I believe in, then I am not movitivated to sell it for any amount of compensation.
Selling as an Integrator, and even in distribution, salespeople make choices--and those choices are not always to sell the product line or service that provides them with the highest commission. If it is not a fit for the customer there is no integrity in shoe-horning it into the customer environment for the sake of 3% more in commission.
I am motivated to sell in this industry because it is the industry I love. There is a passion for the field. May sound crazy to some, yet that is why I stay.
Other factors that come before compensation for me include: a desire to provide my best possible advice to customers, beating out my competitors, the ability to have a level of freedom in reaching my sales goals (i.e. work environment, culture).
Having been a past sales manager I know of many good salespeople I worked with who were motivated more by opportunity for advancement, company benefits, mentoring, educational opportunities, and flexible schedules than they were by compensation.
Don't get me wrong, compensation is vital. I just have not seen it as the biggest motivator.