Reps get paid a percent of sales made. How much? I've heard of agreements as low as 2% and as high as 20%. Most are between 5% and 10%.
Most reps have contracts that give them guarantees of payment for a period, usually six months, after the agreement runs out, if it does. Take a look at http://www.google.com/search?source=ig&hl=en&q=sales+representatives&btnG=Google+Search">this google search for a lot more information.
-- Tim Berry